Merge branch 'mailbox-for-next' of git://git.linaro.org/landing-teams/working/fujitsu/integration

Pull mailbox updates from Jassi Brar.

* 'mailbox-for-next' of git://git.linaro.org/landing-teams/working/fujitsu/integration:
  mailbox: arm_mhu: add driver for ARM MHU controller
  Mailbox: Restructure and simplify PCC mailbox code

Documentation/devicetree/bindings/mailbox/arm-mhu.txt

@@ -0,0 +1,43 @@
+ARM MHU Mailbox Driver
+======================
+
+The ARM's Message-Handling-Unit (MHU) is a mailbox controller that has
+3 independent channels/links to communicate with remote processor(s).
+ MHU links are hardwired on a platform. A link raises interrupt for any
+received data. However, there is no specified way of knowing if the sent
+data has been read by the remote. This driver assumes the sender polls
+STAT register and the remote clears it after having read the data.
+The last channel is specified to be a 'Secure' resource, hence can't be
+used by Linux running NS.
+
+Mailbox Device Node:
+====================
+
+Required properties:
+--------------------
+- compatible:		Shall be "arm,mhu" & "arm,primecell"
+- reg:			Contains the mailbox register address range (base
+			address and length)
+- #mbox-cells		Shall be 1 - the index of the channel needed.
+- interrupts:		Contains the interrupt information corresponding to
+			each of the 3 links of MHU.
+
+Example:
+--------
+
+	mhu: mailbox@2b1f0000 {
+		#mbox-cells = <1>;
+		compatible = "arm,mhu", "arm,primecell";
+		reg = <0 0x2b1f0000 0x1000>;
+		interrupts = <0 36 4>, /* LP-NonSecure */
+			     <0 35 4>, /* HP-NonSecure */
+			     <0 37 4>; /* Secure */
+		clocks = <&clock 0 2 1>;
+		clock-names = "apb_pclk";
+	};
+
+	mhu_client: scb@2e000000 {
+		compatible = "fujitsu,mb86s70-scb-1.0";
+		reg = <0 0x2e000000 0x4000>;
+		mboxes = <&mhu 1>; /* HP-NonSecure */
+	};

drivers/mailbox/Kconfig

@@ -6,6 +6,15 @@ menuconfig MAILBOX
 	  signals. Say Y if your platform supports hardware mailboxes.
 
 if MAILBOX
+
+config ARM_MHU
+	tristate "ARM MHU Mailbox"
+	depends on ARM_AMBA
+	help
+	  Say Y here if you want to build the ARM MHU controller driver.
+	  The controller has 3 mailbox channels, the last of which can be
+	  used in Secure mode only.
+
 config PL320_MBOX
 	bool "ARM PL320 Mailbox"
 	depends on ARM_AMBA

drivers/mailbox/Makefile

@@ -2,6 +2,8 @@
 
 obj-$(CONFIG_MAILBOX)		+= mailbox.o
 
+obj-$(CONFIG_ARM_MHU)	+= arm_mhu.o
+
 obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
 
 obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o

drivers/mailbox/arm_mhu.c

@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
+ * Copyright (C) 2015 Linaro Ltd.
+ * Author: Jassi Brar <jaswinder.singh@linaro.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/amba/bus.h>
+#include <linux/mailbox_controller.h>
+
+#define INTR_STAT_OFS	0x0
+#define INTR_SET_OFS	0x8
+#define INTR_CLR_OFS	0x10
+
+#define MHU_LP_OFFSET	0x0
+#define MHU_HP_OFFSET	0x20
+#define MHU_SEC_OFFSET	0x200
+#define TX_REG_OFFSET	0x100
+
+#define MHU_CHANS	3
+
+struct mhu_link {
+	unsigned irq;
+	void __iomem *tx_reg;
+	void __iomem *rx_reg;
+};
+
+struct arm_mhu {
+	void __iomem *base;
+	struct mhu_link mlink[MHU_CHANS];
+	struct mbox_chan chan[MHU_CHANS];
+	struct mbox_controller mbox;
+};
+
+static irqreturn_t mhu_rx_interrupt(int irq, void *p)
+{
+	struct mbox_chan *chan = p;
+	struct mhu_link *mlink = chan->con_priv;
+	u32 val;
+
+	val = readl_relaxed(mlink->rx_reg + INTR_STAT_OFS);
+	if (!val)
+		return IRQ_NONE;
+
+	mbox_chan_received_data(chan, (void *)&val);
+
+	writel_relaxed(val, mlink->rx_reg + INTR_CLR_OFS);
+
+	return IRQ_HANDLED;
+}
+
+static bool mhu_last_tx_done(struct mbox_chan *chan)
+{
+	struct mhu_link *mlink = chan->con_priv;
+	u32 val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
+
+	return (val == 0);
+}
+
+static int mhu_send_data(struct mbox_chan *chan, void *data)
+{
+	struct mhu_link *mlink = chan->con_priv;
+	u32 *arg = data;
+
+	writel_relaxed(*arg, mlink->tx_reg + INTR_SET_OFS);
+
+	return 0;
+}
+
+static int mhu_startup(struct mbox_chan *chan)
+{
+	struct mhu_link *mlink = chan->con_priv;
+	u32 val;
+	int ret;
+
+	val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
+	writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);
+
+	ret = request_irq(mlink->irq, mhu_rx_interrupt,
+			  IRQF_SHARED, "mhu_link", chan);
+	if (ret) {
+		dev_err(chan->mbox->dev,
+			"Unable to aquire IRQ %d\n", mlink->irq);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void mhu_shutdown(struct mbox_chan *chan)
+{
+	struct mhu_link *mlink = chan->con_priv;
+
+	free_irq(mlink->irq, chan);
+}
+
+static struct mbox_chan_ops mhu_ops = {
+	.send_data = mhu_send_data,
+	.startup = mhu_startup,
+	.shutdown = mhu_shutdown,
+	.last_tx_done = mhu_last_tx_done,
+};
+
+static int mhu_probe(struct amba_device *adev, const struct amba_id *id)
+{
+	int i, err;
+	struct arm_mhu *mhu;
+	struct device *dev = &adev->dev;
+	int mhu_reg[MHU_CHANS] = {MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET};
+
+	/* Allocate memory for device */
+	mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
+	if (!mhu)
+		return -ENOMEM;
+
+	mhu->base = devm_ioremap_resource(dev, &adev->res);
+	if (IS_ERR(mhu->base)) {
+		dev_err(dev, "ioremap failed\n");
+		return PTR_ERR(mhu->base);
+	}
+
+	for (i = 0; i < MHU_CHANS; i++) {
+		mhu->chan[i].con_priv = &mhu->mlink[i];
+		mhu->mlink[i].irq = adev->irq[i];
+		mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
+		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
+	}
+
+	mhu->mbox.dev = dev;
+	mhu->mbox.chans = &mhu->chan[0];
+	mhu->mbox.num_chans = MHU_CHANS;
+	mhu->mbox.ops = &mhu_ops;
+	mhu->mbox.txdone_irq = false;
+	mhu->mbox.txdone_poll = true;
+	mhu->mbox.txpoll_period = 10;
+
+	amba_set_drvdata(adev, mhu);
+
+	err = mbox_controller_register(&mhu->mbox);
+	if (err) {
+		dev_err(dev, "Failed to register mailboxes %d\n", err);
+		return err;
+	}
+
+	dev_info(dev, "ARM MHU Mailbox registered\n");
+	return 0;
+}
+
+static int mhu_remove(struct amba_device *adev)
+{
+	struct arm_mhu *mhu = amba_get_drvdata(adev);
+
+	mbox_controller_unregister(&mhu->mbox);
+
+	return 0;
+}
+
+static struct amba_id mhu_ids[] = {
+	{
+		.id	= 0x1bb098,
+		.mask	= 0xffffff,
+	},
+	{ 0, 0 },
+};
+MODULE_DEVICE_TABLE(amba, mhu_ids);
+
+static struct amba_driver arm_mhu_driver = {
+	.drv = {
+		.name	= "mhu",
+	},
+	.id_table	= mhu_ids,
+	.probe		= mhu_probe,
+	.remove		= mhu_remove,
+};
+module_amba_driver(arm_mhu_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ARM MHU Driver");
+MODULE_AUTHOR("Jassi Brar <jassisinghbrar@gmail.com>");

drivers/mailbox/pcc.c

@@ -20,10 +20,35 @@
  *  shared memory regions as defined in the PCC table entries. The PCC
  *  specification supports a Doorbell mechanism for the PCC clients
  *  to notify the platform about new data. This Doorbell information
- *  is also specified in each PCC table entry. See pcc_send_data()
- *  and pcc_tx_done() for basic mode of operation.
+ *  is also specified in each PCC table entry.
  *
- *  For more details about PCC, please see the ACPI specification from
+ *  Typical high level flow of operation is:
+ *
+ *  PCC Reads:
+ *  * Client tries to acquire a channel lock.
+ *  * After it is acquired it writes READ cmd in communication region cmd
+ *		address.
+ *  * Client issues mbox_send_message() which rings the PCC doorbell
+ *		for its PCC channel.
+ *  * If command completes, then client has control over channel and
+ *		it can proceed with its reads.
+ *  * Client releases lock.
+ *
+ *  PCC Writes:
+ *  * Client tries to acquire channel lock.
+ *  * Client writes to its communication region after it acquires a
+ *		channel lock.
+ *  * Client writes WRITE cmd in communication region cmd address.
+ *  * Client issues mbox_send_message() which rings the PCC doorbell
+ *		for its PCC channel.
+ *  * If command completes, then writes have succeded and it can release
+ *		the channel lock.
+ *
+ *  There is a Nominal latency defined for each channel which indicates
+ *  how long to wait until a command completes. If command is not complete
+ *  the client needs to retry or assume failure.
+ *
+ *	For more details about PCC, please see the ACPI specification from
  *  http://www.uefi.org/ACPIv5.1 Section 14.
  *
  *  This file implements PCC as a Mailbox controller and allows for PCC
@@ -42,8 +67,6 @@
 #include "mailbox.h"
 
 #define MAX_PCC_SUBSPACES	256
-#define PCCS_SS_SIG_MAGIC	0x50434300
-#define PCC_CMD_COMPLETE	0x1
 
 static struct mbox_chan *pcc_mbox_channels;
 
@@ -70,23 +93,6 @@ static struct mbox_chan *get_pcc_channel(int id)
 	return pcc_chan;
 }
 
-/**
- * get_subspace_id - Given a Mailbox channel, find out the
- *		PCC subspace id.
- * @chan: Pointer to Mailbox Channel from which we want
- *		the index.
- * Return: Errno if not found, else positive index number.
- */
-static int get_subspace_id(struct mbox_chan *chan)
-{
-	unsigned int id = chan - pcc_mbox_channels;
-
-	if (id < 0 || id > pcc_mbox_ctrl.num_chans)
-		return -ENOENT;
-
-	return id;
-}
-
 /**
  * pcc_mbox_request_channel - PCC clients call this function to
  *		request a pointer to their PCC subspace, from which they
@@ -117,7 +123,7 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
 	chan = get_pcc_channel(subspace_id);
 
 	if (!chan || chan->cl) {
-		dev_err(dev, "%s: PCC mailbox not free\n", __func__);
+		dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
 		return ERR_PTR(-EBUSY);
 	}
 
@@ -161,81 +167,30 @@ void pcc_mbox_free_channel(struct mbox_chan *chan)
 EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
 
 /**
- * pcc_tx_done - Callback from Mailbox controller code to
- *		check if PCC message transmission completed.
- * @chan: Pointer to Mailbox channel on which previous
- *		transmission occurred.
- *
- * Return: TRUE if succeeded.
- */
-static bool pcc_tx_done(struct mbox_chan *chan)
-{
-	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
-	struct acpi_pcct_shared_memory *generic_comm_base =
-		(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
-	u16 cmd_delay = pcct_ss->latency;
-	unsigned int retries = 0;
-
-	/* Try a few times while waiting for platform to consume */
-	while (!(readw_relaxed(&generic_comm_base->status)
-		    & PCC_CMD_COMPLETE)) {
-
-		if (retries++ < 5)
-			udelay(cmd_delay);
-		else {
-			/*
-			 * If the remote is dead, this will cause the Mbox
-			 * controller to timeout after mbox client.tx_tout
-			 * msecs.
-			 */
-			pr_err("PCC platform did not respond.\n");
-			return false;
-		}
-	}
-	return true;
-}
-
-/**
- * pcc_send_data - Called from Mailbox Controller code to finally
- *	transmit data over channel.
+ * pcc_send_data - Called from Mailbox Controller code. Used
+ *		here only to ring the channel doorbell. The PCC client
+ *		specific read/write is done in the client driver in
+ *		order to maintain atomicity over PCC channel once
+ *		OS has control over it. See above for flow of operations.
  * @chan: Pointer to Mailbox channel over which to send data.
- * @data: Actual data to be written over channel.
+ * @data: Client specific data written over channel. Used here
+ *		only for debug after PCC transaction completes.
  *
  * Return: Err if something failed else 0 for success.
  */
 static int pcc_send_data(struct mbox_chan *chan, void *data)
 {
 	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
-	struct acpi_pcct_shared_memory *generic_comm_base =
-		(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
 	struct acpi_generic_address doorbell;
 	u64 doorbell_preserve;
 	u64 doorbell_val;
 	u64 doorbell_write;
-	u16 cmd = *(u16 *) data;
-	u16 ss_idx = -1;
-
-	ss_idx = get_subspace_id(chan);
-
-	if (ss_idx < 0) {
-		pr_err("Invalid Subspace ID from PCC client\n");
-		return -EINVAL;
-	}
 
 	doorbell = pcct_ss->doorbell_register;
 	doorbell_preserve = pcct_ss->preserve_mask;
 	doorbell_write = pcct_ss->write_mask;
 
-	/* Write to the shared comm region. */
-	writew(cmd, &generic_comm_base->command);
-
-	/* Write Subspace MAGIC value so platform can identify destination. */
-	writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
-
-	/* Flip CMD COMPLETE bit */
-	writew(0, &generic_comm_base->status);
-
-	/* Sync notification from OSPM to Platform. */
+	/* Sync notification from OS to Platform. */
 	acpi_read(&doorbell_val, &doorbell);
 	acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
 			&doorbell);
@@ -245,7 +200,6 @@ static int pcc_send_data(struct mbox_chan *chan, void *data)
 
 static struct mbox_chan_ops pcc_chan_ops = {
 	.send_data = pcc_send_data,
-	.last_tx_done = pcc_tx_done,
 };
 
 /**
@@ -351,8 +305,6 @@ static int pcc_mbox_probe(struct platform_device *pdev)
 
 	pcc_mbox_ctrl.chans = pcc_mbox_channels;
 	pcc_mbox_ctrl.ops = &pcc_chan_ops;
-	pcc_mbox_ctrl.txdone_poll = true;
-	pcc_mbox_ctrl.txpoll_period = 10;
 	pcc_mbox_ctrl.dev = &pdev->dev;
 
 	pr_info("Registering PCC driver as Mailbox controller\n");