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+/*
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+ * Copyright 2013 Emilio López
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+ * Emilio López <emilio@elopez.com.ar>
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+ *
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+ * Copyright 2013 Chen-Yu Tsai
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+ * Chen-Yu Tsai <wens@csie.org>
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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 as published by
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+ * the Free Software Foundation; either version 2 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ */
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+
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+#include <linux/clk-provider.h>
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+#include <linux/clkdev.h>
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+#include <linux/of.h>
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+#include <linux/of_address.h>
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+#include <linux/slab.h>
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+
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+static DEFINE_SPINLOCK(gmac_lock);
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+
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+/**
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+ * sun7i_a20_gmac_clk_setup - Setup function for A20/A31 GMAC clock module
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+ *
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+ * This clock looks something like this
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+ * ________________________
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+ * MII TX clock from PHY >-----|___________ _________|----> to GMAC core
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+ * GMAC Int. RGMII TX clk >----|___________\__/__gate---|----> to PHY
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+ * Ext. 125MHz RGMII TX clk >--|__divider__/ |
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+ * |________________________|
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+ *
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+ * The external 125 MHz reference is optional, i.e. GMAC can use its
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+ * internal TX clock just fine. The A31 GMAC clock module does not have
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+ * the divider controls for the external reference.
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+ *
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+ * To keep it simple, let the GMAC use either the MII TX clock for MII mode,
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+ * and its internal TX clock for GMII and RGMII modes. The GMAC driver should
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+ * select the appropriate source and gate/ungate the output to the PHY.
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+ *
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+ * Only the GMAC should use this clock. Altering the clock so that it doesn't
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+ * match the GMAC's operation parameters will result in the GMAC not being
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+ * able to send traffic out. The GMAC driver should set the clock rate and
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+ * enable/disable this clock to configure the required state. The clock
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+ * driver then responds by auto-reparenting the clock.
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+ */
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+
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+#define SUN7I_A20_GMAC_GPIT 2
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+#define SUN7I_A20_GMAC_MASK 0x3
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+#define SUN7I_A20_GMAC_PARENTS 2
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+
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+static void __init sun7i_a20_gmac_clk_setup(struct device_node *node)
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+{
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+ struct clk *clk;
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+ struct clk_mux *mux;
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+ struct clk_gate *gate;
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+ const char *clk_name = node->name;
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+ const char *parents[SUN7I_A20_GMAC_PARENTS];
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+ void *reg;
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+
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+ if (of_property_read_string(node, "clock-output-names", &clk_name))
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+ return;
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+
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+ /* allocate mux and gate clock structs */
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+ mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
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+ if (!mux)
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+ return;
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+
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+ gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
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+ if (!gate)
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+ goto free_mux;
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+
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+ /* gmac clock requires exactly 2 parents */
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+ parents[0] = of_clk_get_parent_name(node, 0);
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+ parents[1] = of_clk_get_parent_name(node, 1);
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+ if (!parents[0] || !parents[1])
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+ goto free_gate;
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+
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+ reg = of_iomap(node, 0);
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+ if (!reg)
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+ goto free_gate;
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+
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+ /* set up gate and fixed rate properties */
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+ gate->reg = reg;
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+ gate->bit_idx = SUN7I_A20_GMAC_GPIT;
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+ gate->lock = &gmac_lock;
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+ mux->reg = reg;
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+ mux->mask = SUN7I_A20_GMAC_MASK;
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+ mux->flags = CLK_MUX_INDEX_BIT;
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+ mux->lock = &gmac_lock;
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+
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+ clk = clk_register_composite(NULL, clk_name,
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+ parents, SUN7I_A20_GMAC_PARENTS,
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+ &mux->hw, &clk_mux_ops,
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+ NULL, NULL,
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+ &gate->hw, &clk_gate_ops,
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+ 0);
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+
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+ if (IS_ERR(clk))
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+ goto iounmap_reg;
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+
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+ of_clk_add_provider(node, of_clk_src_simple_get, clk);
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+ clk_register_clkdev(clk, clk_name, NULL);
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+
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+ return;
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+
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+iounmap_reg:
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+ iounmap(reg);
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+free_gate:
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+ kfree(gate);
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+free_mux:
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+ kfree(mux);
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+}
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+CLK_OF_DECLARE(sun7i_a20_gmac, "allwinner,sun7i-a20-gmac-clk",
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+ sun7i_a20_gmac_clk_setup);
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