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-/*
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- * clkt_clksel.c - OMAP2/3/4 clksel clock functions
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- *
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- * Copyright (C) 2005-2008 Texas Instruments, Inc.
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- * Copyright (C) 2004-2010 Nokia Corporation
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- *
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- * Contacts:
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- * Richard Woodruff <r-woodruff2@ti.com>
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- * Paul Walmsley
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- *
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- * This program is free software; you can redistribute it and/or modify
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- * it under the terms of the GNU General Public License version 2 as
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- * published by the Free Software Foundation.
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- *
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- *
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- * clksel clocks are clocks that do not have a fixed parent, or that
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- * can divide their parent's rate, or possibly both at the same time, based
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- * on the contents of a hardware register bitfield.
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- *
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- * All of the various mux and divider settings can be encoded into
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- * struct clksel* data structures, and then these can be autogenerated
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- * from some hardware database for each new chip generation. This
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- * should avoid the need to write, review, and validate a lot of new
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- * clock code for each new chip, since it can be exported from the SoC
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- * design flow. This is now done on OMAP4.
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- *
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- * The fusion of mux and divider clocks is a software creation. In
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- * hardware reality, the multiplexer (parent selection) and the
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- * divider exist separately. XXX At some point these clksel clocks
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- * should be split into "divider" clocks and "mux" clocks to better
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- * match the hardware.
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- *
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- * (The name "clksel" comes from the name of the corresponding
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- * register field in the OMAP2/3 family of SoCs.)
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- *
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- * XXX Currently these clocks are only used in the OMAP2/3/4 code, but
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- * many of the OMAP1 clocks should be convertible to use this
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- * mechanism.
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- */
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-#undef DEBUG
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-
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-#include <linux/kernel.h>
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-#include <linux/errno.h>
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-#include <linux/clk-provider.h>
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-#include <linux/io.h>
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-#include <linux/bug.h>
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-
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-#include "clock.h"
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-
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-/* Private functions */
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-
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-/**
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- * _get_clksel_by_parent() - return clksel struct for a given clk & parent
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- * @clk: OMAP struct clk ptr to inspect
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- * @src_clk: OMAP struct clk ptr of the parent clk to search for
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- *
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- * Scan the struct clksel array associated with the clock to find
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- * the element associated with the supplied parent clock address.
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- * Returns a pointer to the struct clksel on success or NULL on error.
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- */
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-static const struct clksel *_get_clksel_by_parent(struct clk_hw_omap *clk,
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- struct clk *src_clk)
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-{
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- const struct clksel *clks;
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-
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- if (!src_clk)
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- return NULL;
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-
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- for (clks = clk->clksel; clks->parent; clks++)
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- if (clks->parent == src_clk)
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- break; /* Found the requested parent */
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-
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- if (!clks->parent) {
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- /* This indicates a data problem */
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- WARN(1, "clock: %s: could not find parent clock %s in clksel array\n",
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- __clk_get_name(clk->hw.clk), __clk_get_name(src_clk));
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- return NULL;
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- }
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-
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- return clks;
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-}
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-
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-/**
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- * _write_clksel_reg() - program a clock's clksel register in hardware
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- * @clk: struct clk * to program
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- * @v: clksel bitfield value to program (with LSB at bit 0)
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- *
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- * Shift the clksel register bitfield value @v to its appropriate
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- * location in the clksel register and write it in. This function
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- * will ensure that the write to the clksel_reg reaches its
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- * destination before returning -- important since PRM and CM register
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- * accesses can be quite slow compared to ARM cycles -- but does not
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- * take into account any time the hardware might take to switch the
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- * clock source.
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- */
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-static void _write_clksel_reg(struct clk_hw_omap *clk, u32 field_val)
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-{
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- u32 v;
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-
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- v = omap2_clk_readl(clk, clk->clksel_reg);
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- v &= ~clk->clksel_mask;
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- v |= field_val << __ffs(clk->clksel_mask);
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- omap2_clk_writel(v, clk, clk->clksel_reg);
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-
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- v = omap2_clk_readl(clk, clk->clksel_reg); /* OCP barrier */
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-}
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-
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-/**
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- * _clksel_to_divisor() - turn clksel field value into integer divider
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- * @clk: OMAP struct clk to use
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- * @field_val: register field value to find
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- *
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- * Given a struct clk of a rate-selectable clksel clock, and a register field
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- * value to search for, find the corresponding clock divisor. The register
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- * field value should be pre-masked and shifted down so the LSB is at bit 0
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- * before calling. Returns 0 on error or returns the actual integer divisor
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- * upon success.
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- */
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-static u32 _clksel_to_divisor(struct clk_hw_omap *clk, u32 field_val)
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-{
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- const struct clksel *clks;
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- const struct clksel_rate *clkr;
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- struct clk *parent;
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-
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- parent = __clk_get_parent(clk->hw.clk);
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-
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- clks = _get_clksel_by_parent(clk, parent);
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- if (!clks)
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- return 0;
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-
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- for (clkr = clks->rates; clkr->div; clkr++) {
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- if (!(clkr->flags & cpu_mask))
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- continue;
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-
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- if (clkr->val == field_val)
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- break;
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- }
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-
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- if (!clkr->div) {
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- /* This indicates a data error */
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- WARN(1, "clock: %s: could not find fieldval %d for parent %s\n",
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- __clk_get_name(clk->hw.clk), field_val,
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- __clk_get_name(parent));
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- return 0;
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- }
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-
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- return clkr->div;
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-}
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-
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-/**
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- * _divisor_to_clksel() - turn clksel integer divisor into a field value
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- * @clk: OMAP struct clk to use
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- * @div: integer divisor to search for
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- *
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- * Given a struct clk of a rate-selectable clksel clock, and a clock
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- * divisor, find the corresponding register field value. Returns the
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- * register field value _before_ left-shifting (i.e., LSB is at bit
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- * 0); or returns 0xFFFFFFFF (~0) upon error.
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- */
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-static u32 _divisor_to_clksel(struct clk_hw_omap *clk, u32 div)
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-{
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- const struct clksel *clks;
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- const struct clksel_rate *clkr;
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- struct clk *parent;
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-
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- /* should never happen */
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- WARN_ON(div == 0);
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-
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- parent = __clk_get_parent(clk->hw.clk);
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- clks = _get_clksel_by_parent(clk, parent);
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- if (!clks)
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- return ~0;
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-
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- for (clkr = clks->rates; clkr->div; clkr++) {
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- if (!(clkr->flags & cpu_mask))
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- continue;
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-
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- if (clkr->div == div)
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- break;
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- }
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-
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- if (!clkr->div) {
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- pr_err("clock: %s: could not find divisor %d for parent %s\n",
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- __clk_get_name(clk->hw.clk), div,
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- __clk_get_name(parent));
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- return ~0;
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- }
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-
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- return clkr->val;
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-}
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-
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-/**
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- * _read_divisor() - get current divisor applied to parent clock (from hdwr)
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- * @clk: OMAP struct clk to use.
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- *
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- * Read the current divisor register value for @clk that is programmed
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- * into the hardware, convert it into the actual divisor value, and
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- * return it; or return 0 on error.
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- */
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-static u32 _read_divisor(struct clk_hw_omap *clk)
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-{
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- u32 v;
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-
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- if (!clk->clksel || !clk->clksel_mask)
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- return 0;
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-
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- v = omap2_clk_readl(clk, clk->clksel_reg);
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- v &= clk->clksel_mask;
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- v >>= __ffs(clk->clksel_mask);
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-
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- return _clksel_to_divisor(clk, v);
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-}
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-
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-/* Public functions */
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-
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-/**
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- * omap2_clksel_round_rate_div() - find divisor for the given clock and rate
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- * @clk: OMAP struct clk to use
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- * @target_rate: desired clock rate
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- * @new_div: ptr to where we should store the divisor
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- *
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- * Finds 'best' divider value in an array based on the source and target
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- * rates. The divider array must be sorted with smallest divider first.
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- * This function is also used by the DPLL3 M2 divider code.
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- *
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- * Returns the rounded clock rate or returns 0xffffffff on error.
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- */
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-u32 omap2_clksel_round_rate_div(struct clk_hw_omap *clk,
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- unsigned long target_rate,
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- u32 *new_div)
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-{
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- unsigned long test_rate;
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- const struct clksel *clks;
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- const struct clksel_rate *clkr;
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- u32 last_div = 0;
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- struct clk *parent;
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- unsigned long parent_rate;
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- const char *clk_name;
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-
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- parent = __clk_get_parent(clk->hw.clk);
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- clk_name = __clk_get_name(clk->hw.clk);
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- parent_rate = __clk_get_rate(parent);
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-
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- if (!clk->clksel || !clk->clksel_mask)
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- return ~0;
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-
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- pr_debug("clock: clksel_round_rate_div: %s target_rate %ld\n",
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- clk_name, target_rate);
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-
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- *new_div = 1;
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-
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- clks = _get_clksel_by_parent(clk, parent);
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- if (!clks)
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- return ~0;
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-
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- for (clkr = clks->rates; clkr->div; clkr++) {
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- if (!(clkr->flags & cpu_mask))
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- continue;
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-
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- /* Sanity check */
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- if (clkr->div <= last_div)
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- pr_err("clock: %s: clksel_rate table not sorted\n",
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- clk_name);
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-
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- last_div = clkr->div;
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-
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- test_rate = parent_rate / clkr->div;
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-
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- if (test_rate <= target_rate)
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- break; /* found it */
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- }
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-
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- if (!clkr->div) {
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- pr_err("clock: %s: could not find divisor for target rate %ld for parent %s\n",
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- clk_name, target_rate, __clk_get_name(parent));
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- return ~0;
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- }
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-
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- *new_div = clkr->div;
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-
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- pr_debug("clock: new_div = %d, new_rate = %ld\n", *new_div,
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- (parent_rate / clkr->div));
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-
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- return parent_rate / clkr->div;
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-}
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-
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-/*
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- * Clocktype interface functions to the OMAP clock code
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- * (i.e., those used in struct clk field function pointers, etc.)
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- */
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-
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-/**
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- * omap2_clksel_find_parent_index() - return the array index of the current
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- * hardware parent of @hw
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- * @hw: struct clk_hw * to find the current hardware parent of
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- *
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- * Given a struct clk_hw pointer @hw to the 'hw' member of a struct
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- * clk_hw_omap record representing a source-selectable hardware clock,
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- * read the hardware register and determine what its parent is
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- * currently set to. Intended to be called only by the common clock
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- * framework struct clk_hw_ops.get_parent function pointer. Return
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- * the array index of this parent clock upon success -- there is no
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- * way to return an error, so if we encounter an error, just WARN()
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- * and pretend that we know that we're doing.
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- */
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-u8 omap2_clksel_find_parent_index(struct clk_hw *hw)
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-{
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- struct clk_hw_omap *clk = to_clk_hw_omap(hw);
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- const struct clksel *clks;
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- const struct clksel_rate *clkr;
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- u32 r, found = 0;
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- struct clk *parent;
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- const char *clk_name;
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- int ret = 0, f = 0;
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-
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- parent = __clk_get_parent(hw->clk);
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- clk_name = __clk_get_name(hw->clk);
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-
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- /* XXX should be able to return an error */
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- WARN((!clk->clksel || !clk->clksel_mask),
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- "clock: %s: attempt to call on a non-clksel clock", clk_name);
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-
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- r = omap2_clk_readl(clk, clk->clksel_reg) & clk->clksel_mask;
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- r >>= __ffs(clk->clksel_mask);
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-
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- for (clks = clk->clksel; clks->parent && !found; clks++) {
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- for (clkr = clks->rates; clkr->div && !found; clkr++) {
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- if (!(clkr->flags & cpu_mask))
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- continue;
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-
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- if (clkr->val == r) {
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- found = 1;
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- ret = f;
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- }
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- }
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- f++;
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- }
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-
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- /* This indicates a data error */
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- WARN(!found, "clock: %s: init parent: could not find regval %0x\n",
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- clk_name, r);
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-
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- return ret;
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-}
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-
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-
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-/**
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- * omap2_clksel_recalc() - function ptr to pass via struct clk .recalc field
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- * @clk: struct clk *
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- *
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- * This function is intended to be called only by the clock framework.
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- * Each clksel clock should have its struct clk .recalc field set to this
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- * function. Returns the clock's current rate, based on its parent's rate
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- * and its current divisor setting in the hardware.
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- */
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-unsigned long omap2_clksel_recalc(struct clk_hw *hw, unsigned long parent_rate)
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-{
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- unsigned long rate;
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- u32 div = 0;
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- struct clk_hw_omap *clk = to_clk_hw_omap(hw);
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-
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- if (!parent_rate)
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- return 0;
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-
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- div = _read_divisor(clk);
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- if (!div)
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- rate = parent_rate;
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- else
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- rate = parent_rate / div;
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-
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- pr_debug("%s: recalc'd %s's rate to %lu (div %d)\n", __func__,
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- __clk_get_name(hw->clk), rate, div);
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-
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- return rate;
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-}
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-
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-/**
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- * omap2_clksel_round_rate() - find rounded rate for the given clock and rate
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- * @clk: OMAP struct clk to use
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- * @target_rate: desired clock rate
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- *
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- * This function is intended to be called only by the clock framework.
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- * Finds best target rate based on the source clock and possible dividers.
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- * rates. The divider array must be sorted with smallest divider first.
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- *
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- * Returns the rounded clock rate or returns 0xffffffff on error.
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- */
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-long omap2_clksel_round_rate(struct clk_hw *hw, unsigned long target_rate,
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- unsigned long *parent_rate)
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-{
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- struct clk_hw_omap *clk = to_clk_hw_omap(hw);
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- u32 new_div;
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-
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- return omap2_clksel_round_rate_div(clk, target_rate, &new_div);
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-}
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-
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-/**
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- * omap2_clksel_set_rate() - program clock rate in hardware
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- * @clk: struct clk * to program rate
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- * @rate: target rate to program
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- *
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- * This function is intended to be called only by the clock framework.
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- * Program @clk's rate to @rate in the hardware. The clock can be
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- * either enabled or disabled when this happens, although if the clock
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- * is enabled, some downstream devices may glitch or behave
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- * unpredictably when the clock rate is changed - this depends on the
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- * hardware. This function does not currently check the usecount of
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- * the clock, so if multiple drivers are using the clock, and the rate
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- * is changed, they will all be affected without any notification.
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- * Returns -EINVAL upon error, or 0 upon success.
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- */
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-int omap2_clksel_set_rate(struct clk_hw *hw, unsigned long rate,
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- unsigned long parent_rate)
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-{
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- struct clk_hw_omap *clk = to_clk_hw_omap(hw);
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- u32 field_val, validrate, new_div = 0;
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-
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- if (!clk->clksel || !clk->clksel_mask)
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- return -EINVAL;
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-
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- validrate = omap2_clksel_round_rate_div(clk, rate, &new_div);
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|
- if (validrate != rate)
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|
- return -EINVAL;
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|
-
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- field_val = _divisor_to_clksel(clk, new_div);
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|
- if (field_val == ~0)
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|
- return -EINVAL;
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|
-
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- _write_clksel_reg(clk, field_val);
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-
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- pr_debug("clock: %s: set rate to %ld\n", __clk_get_name(hw->clk),
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- __clk_get_rate(hw->clk));
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-
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- return 0;
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-}
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|
-
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|
|
-/*
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|
- * Clksel parent setting function - not passed in struct clk function
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|
- * pointer - instead, the OMAP clock code currently assumes that any
|
|
|
- * parent-setting clock is a clksel clock, and calls
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|
- * omap2_clksel_set_parent() by default
|
|
|
- */
|
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|
-
|
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|
-/**
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|
- * omap2_clksel_set_parent() - change a clock's parent clock
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|
|
- * @clk: struct clk * of the child clock
|
|
|
- * @new_parent: struct clk * of the new parent clock
|
|
|
- *
|
|
|
- * This function is intended to be called only by the clock framework.
|
|
|
- * Change the parent clock of clock @clk to @new_parent. This is
|
|
|
- * intended to be used while @clk is disabled. This function does not
|
|
|
- * currently check the usecount of the clock, so if multiple drivers
|
|
|
- * are using the clock, and the parent is changed, they will all be
|
|
|
- * affected without any notification. Returns -EINVAL upon error, or
|
|
|
- * 0 upon success.
|
|
|
- */
|
|
|
-int omap2_clksel_set_parent(struct clk_hw *hw, u8 field_val)
|
|
|
-{
|
|
|
- struct clk_hw_omap *clk = to_clk_hw_omap(hw);
|
|
|
-
|
|
|
- if (!clk->clksel || !clk->clksel_mask)
|
|
|
- return -EINVAL;
|
|
|
-
|
|
|
- _write_clksel_reg(clk, field_val);
|
|
|
- return 0;
|
|
|
-}
|