mailbox: rockchip: Add Rockchip mailbox driver

This driver is found on RK3368 SoCs.

The Mailbox module is a simple APB peripheral that allows both
the Cortex-A53 MCU system to communicate by writing operation to
generate interrupt.
The registers are accessible by both CPU via APB interface.

The Mailbox has the following main features:

1) Support dual-core system: Cortex-A53 and MCU.
2) Support APB interface.
3) Support four mailbox elements, each element includes one data word,
   one command word register and one flag bit that can represent
   one interrupt.
4) Four interrupts to Cortex-A53.
5) Four interrupts to MCU.
6) Provide 32 lock registers for software to use to indicate whether
   mailbox is occupied.

[Jassi: Removed unused variable buf_base]

Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/Kconfig

@@ -43,6 +43,15 @@ config OMAP_MBOX_KFIFO_SIZE
 	  This can also be changed at runtime (via the mbox_kfifo_size
 	  module parameter).
 
+config ROCKCHIP_MBOX
+	bool "Rockchip Soc Intergrated Mailbox Support"
+	depends on ARCH_ROCKCHIP || COMPILE_TEST
+	help
+	  This driver provides support for inter-processor communication
+	  between CPU cores and MCU processor on Some Rockchip SOCs.
+	  Please check it that the Soc you use have Mailbox hardware.
+	  Say Y here if you want to use the Rockchip Mailbox support.
+
 config PCC
 	bool "Platform Communication Channel Driver"
 	depends on ACPI

drivers/mailbox/Makefile

@@ -10,6 +10,8 @@ obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
 
 obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o
 
+obj-$(CONFIG_ROCKCHIP_MBOX)	+= rockchip-mailbox.o
+
 obj-$(CONFIG_PCC)		+= pcc.o
 
 obj-$(CONFIG_ALTERA_MBOX)	+= mailbox-altera.o

drivers/mailbox/rockchip-mailbox.c

@@ -0,0 +1,283 @@
+/*
+ * Copyright (c) 2015, Fuzhou Rockchip Electronics Co., Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#define MAILBOX_A2B_INTEN		0x00
+#define MAILBOX_A2B_STATUS		0x04
+#define MAILBOX_A2B_CMD(x)		(0x08 + (x) * 8)
+#define MAILBOX_A2B_DAT(x)		(0x0c + (x) * 8)
+
+#define MAILBOX_B2A_INTEN		0x28
+#define MAILBOX_B2A_STATUS		0x2C
+#define MAILBOX_B2A_CMD(x)		(0x30 + (x) * 8)
+#define MAILBOX_B2A_DAT(x)		(0x34 + (x) * 8)
+
+struct rockchip_mbox_msg {
+	u32 cmd;
+	int rx_size;
+};
+
+struct rockchip_mbox_data {
+	int num_chans;
+};
+
+struct rockchip_mbox_chan {
+	int idx;
+	int irq;
+	struct rockchip_mbox_msg *msg;
+	struct rockchip_mbox *mb;
+};
+
+struct rockchip_mbox {
+	struct mbox_controller mbox;
+	struct clk *pclk;
+	void __iomem *mbox_base;
+
+	/* The maximum size of buf for each channel */
+	u32 buf_size;
+
+	struct rockchip_mbox_chan *chans;
+};
+
+static int rockchip_mbox_send_data(struct mbox_chan *chan, void *data)
+{
+	struct rockchip_mbox *mb = dev_get_drvdata(chan->mbox->dev);
+	struct rockchip_mbox_msg *msg = data;
+	struct rockchip_mbox_chan *chans = mb->chans;
+
+	if (!msg)
+		return -EINVAL;
+
+	if (msg->rx_size > mb->buf_size) {
+		dev_err(mb->mbox.dev, "Transmit size over buf size(%d)\n",
+			mb->buf_size);
+		return -EINVAL;
+	}
+
+	dev_dbg(mb->mbox.dev, "Chan[%d]: A2B message, cmd 0x%08x\n",
+		chans->idx, msg->cmd);
+
+	mb->chans[chans->idx].msg = msg;
+
+	writel_relaxed(msg->cmd, mb->mbox_base + MAILBOX_A2B_CMD(chans->idx));
+	writel_relaxed(msg->rx_size, mb->mbox_base +
+		       MAILBOX_A2B_DAT(chans->idx));
+
+	return 0;
+}
+
+static int rockchip_mbox_startup(struct mbox_chan *chan)
+{
+	struct rockchip_mbox *mb = dev_get_drvdata(chan->mbox->dev);
+
+	/* Enable all B2A interrupts */
+	writel_relaxed((1 << mb->mbox.num_chans) - 1,
+		       mb->mbox_base + MAILBOX_B2A_INTEN);
+
+	return 0;
+}
+
+static void rockchip_mbox_shutdown(struct mbox_chan *chan)
+{
+	struct rockchip_mbox *mb = dev_get_drvdata(chan->mbox->dev);
+	struct rockchip_mbox_chan *chans = mb->chans;
+
+	/* Disable all B2A interrupts */
+	writel_relaxed(0, mb->mbox_base + MAILBOX_B2A_INTEN);
+
+	mb->chans[chans->idx].msg = NULL;
+}
+
+static const struct mbox_chan_ops rockchip_mbox_chan_ops = {
+	.send_data	= rockchip_mbox_send_data,
+	.startup	= rockchip_mbox_startup,
+	.shutdown	= rockchip_mbox_shutdown,
+};
+
+static irqreturn_t rockchip_mbox_irq(int irq, void *dev_id)
+{
+	int idx;
+	struct rockchip_mbox *mb = (struct rockchip_mbox *)dev_id;
+	u32 status = readl_relaxed(mb->mbox_base + MAILBOX_B2A_STATUS);
+
+	for (idx = 0; idx < mb->mbox.num_chans; idx++) {
+		if ((status & (1 << idx)) && (irq == mb->chans[idx].irq)) {
+			/* Clear mbox interrupt */
+			writel_relaxed(1 << idx,
+				       mb->mbox_base + MAILBOX_B2A_STATUS);
+			return IRQ_WAKE_THREAD;
+		}
+	}
+
+	return IRQ_NONE;
+}
+
+static irqreturn_t rockchip_mbox_isr(int irq, void *dev_id)
+{
+	int idx;
+	struct rockchip_mbox_msg *msg = NULL;
+	struct rockchip_mbox *mb = (struct rockchip_mbox *)dev_id;
+
+	for (idx = 0; idx < mb->mbox.num_chans; idx++) {
+		if (irq != mb->chans[idx].irq)
+			continue;
+
+		msg = mb->chans[idx].msg;
+		if (!msg) {
+			dev_err(mb->mbox.dev,
+				"Chan[%d]: B2A message is NULL\n", idx);
+			break; /* spurious */
+		}
+
+		mbox_chan_received_data(&mb->mbox.chans[idx], msg);
+		mb->chans[idx].msg = NULL;
+
+		dev_dbg(mb->mbox.dev, "Chan[%d]: B2A message, cmd 0x%08x\n",
+			idx, msg->cmd);
+
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static const struct rockchip_mbox_data rk3368_drv_data = {
+	.num_chans = 4,
+};
+
+static const struct of_device_id rockchip_mbox_of_match[] = {
+	{ .compatible = "rockchip,rk3368-mailbox", .data = &rk3368_drv_data},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, rockchp_mbox_of_match);
+
+static int rockchip_mbox_probe(struct platform_device *pdev)
+{
+	struct rockchip_mbox *mb;
+	const struct of_device_id *match;
+	const struct rockchip_mbox_data *drv_data;
+	struct resource *res;
+	int ret, irq, i;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	match = of_match_node(rockchip_mbox_of_match, pdev->dev.of_node);
+	drv_data = (const struct rockchip_mbox_data *)match->data;
+
+	mb = devm_kzalloc(&pdev->dev, sizeof(*mb), GFP_KERNEL);
+	if (!mb)
+		return -ENOMEM;
+
+	mb->chans = devm_kcalloc(&pdev->dev, drv_data->num_chans,
+				 sizeof(*mb->chans), GFP_KERNEL);
+	if (!mb->chans)
+		return -ENOMEM;
+
+	mb->mbox.chans = devm_kcalloc(&pdev->dev, drv_data->num_chans,
+				      sizeof(*mb->mbox.chans), GFP_KERNEL);
+	if (!mb->mbox.chans)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, mb);
+
+	mb->mbox.dev = &pdev->dev;
+	mb->mbox.num_chans = drv_data->num_chans;
+	mb->mbox.ops = &rockchip_mbox_chan_ops;
+	mb->mbox.txdone_irq = true;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	mb->mbox_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(mb->mbox_base))
+		return PTR_ERR(mb->mbox_base);
+
+	/* Each channel has two buffers for A2B and B2A */
+	mb->buf_size = resource_size(res) / (drv_data->num_chans * 2);
+
+	mb->pclk = devm_clk_get(&pdev->dev, "pclk_mailbox");
+	if (IS_ERR(mb->pclk)) {
+		ret = PTR_ERR(mb->pclk);
+		dev_err(&pdev->dev, "failed to get pclk_mailbox clock: %d\n",
+			ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(mb->pclk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable pclk: %d\n", ret);
+		return ret;
+	}
+
+	for (i = 0; i < mb->mbox.num_chans; i++) {
+		irq = platform_get_irq(pdev, i);
+		if (irq < 0)
+			return irq;
+
+		ret = devm_request_threaded_irq(&pdev->dev, irq,
+						rockchip_mbox_irq,
+						rockchip_mbox_isr, IRQF_ONESHOT,
+						dev_name(&pdev->dev), mb);
+		if (ret < 0)
+			return ret;
+
+		mb->chans[i].idx = i;
+		mb->chans[i].irq = irq;
+		mb->chans[i].mb = mb;
+		mb->chans[i].msg = NULL;
+	}
+
+	ret = mbox_controller_register(&mb->mbox);
+	if (ret < 0)
+		dev_err(&pdev->dev, "Failed to register mailbox: %d\n", ret);
+
+	return ret;
+}
+
+static int rockchip_mbox_remove(struct platform_device *pdev)
+{
+	struct rockchip_mbox *mb = platform_get_drvdata(pdev);
+
+	if (!mb)
+		return -EINVAL;
+
+	mbox_controller_unregister(&mb->mbox);
+
+	return 0;
+}
+
+static struct platform_driver rockchip_mbox_driver = {
+	.probe	= rockchip_mbox_probe,
+	.remove	= rockchip_mbox_remove,
+	.driver = {
+		.name = "rockchip-mailbox",
+		.of_match_table = of_match_ptr(rockchip_mbox_of_match),
+	},
+};
+
+module_platform_driver(rockchip_mbox_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Rockchip mailbox: communicate between CPU cores and MCU");
+MODULE_AUTHOR("Addy Ke <addy.ke@rock-chips.com>");
+MODULE_AUTHOR("Caesar Wang <wxt@rock-chips.com>");