[RFC PATCH 2/3] soc: ti: Add wkup_m3_ipc driver

[Dave Gerlach]

Introduce a wkup_m3_ipc driver to handle communication between the MPU
and Cortex M3 wkup_m3 present on am335x.

This driver is responsible for actually booting the wkup_m3_rproc and
also handling all IPC which is done using the IPC registers in the control
module, a mailbox, and a separate interrupt back from the wkup_m3. A small
API is exposed for executing specific power commands, which include
configuring for low power mode, request a transition to a low power mode,
and status info on a previous transition.

Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
---
 drivers/soc/ti/Kconfig       |  11 +
 drivers/soc/ti/Makefile      |   1 +
 drivers/soc/ti/wkup_m3_ipc.c | 503 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/wkup_m3_ipc.h  |  33 +++
 4 files changed, 548 insertions(+)
 create mode 100644 drivers/soc/ti/wkup_m3_ipc.c
 create mode 100644 include/linux/wkup_m3_ipc.h

diff --git a/drivers/soc/ti/Kconfig b/drivers/soc/ti/Kconfig
index 7266b21..61cda85 100644
--- a/drivers/soc/ti/Kconfig
+++ b/drivers/soc/ti/Kconfig
@@ -28,4 +28,15 @@ config KEYSTONE_NAVIGATOR_DMA
 
 	  If unsure, say N.
 
+config WKUP_M3_IPC
+	bool "TI AM33XX Wkup-M3 IPC Driver"
+	depends on WKUP_M3_RPROC
+	select MAILBOX
+	select OMAP2PLUS_MBOX
+	help
+	  TI AM33XX has a Cortex M3 to handle low power transitions. This IPC
+	  driver provides the necessary API to communicate and use the wkup m3
+	  for PM features like Suspend/Resume and boots the wkup_m3 using
+	  wkup_m3_rproc driver.
+
 endif # SOC_TI
diff --git a/drivers/soc/ti/Makefile b/drivers/soc/ti/Makefile
index 6bed611..b6b8c8b 100644
--- a/drivers/soc/ti/Makefile
+++ b/drivers/soc/ti/Makefile
@@ -3,3 +3,4 @@
 #
 obj-$(CONFIG_KEYSTONE_NAVIGATOR_QMSS)	+= knav_qmss_queue.o knav_qmss_acc.o
 obj-$(CONFIG_KEYSTONE_NAVIGATOR_DMA)	+= knav_dma.o
+obj-$(CONFIG_WKUP_M3_IPC)		+= wkup_m3_ipc.o
diff --git a/drivers/soc/ti/wkup_m3_ipc.c b/drivers/soc/ti/wkup_m3_ipc.c
new file mode 100644
index 0000000..f915da6
--- /dev/null
+++ b/drivers/soc/ti/wkup_m3_ipc.c
@@ -0,0 +1,503 @@
+/*
+ * AMx3 Wkup M3 IPC driver
+ *
+ * Copyright (C) 2014 Texas Instruments, Inc.
+ *
+ * Dave Gerlach <d-gerlach@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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/err.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/omap-mailbox.h>
+#include <linux/platform_device.h>
+#include <linux/remoteproc.h>
+#include <linux/suspend.h>
+#include <linux/wkup_m3_ipc.h>
+
+#define AM33XX_CTRL_IPC_REG_COUNT	0x8
+#define AM33XX_CTRL_IPC_REG_OFFSET(m)	(0x4 + 4 * (m))
+
+/* AM33XX M3_TXEV_EOI register */
+#define AM33XX_CONTROL_M3_TXEV_EOI	0x00
+
+#define AM33XX_M3_TXEV_ACK		(0x1 << 0)
+#define AM33XX_M3_TXEV_ENABLE		(0x0 << 0)
+
+#define IPC_CMD_DS0			0x4
+#define IPC_CMD_STANDBY			0xc
+#define IPC_CMD_RESET			0xe
+#define DS_IPC_DEFAULT			0xffffffff
+#define M3_VERSION_UNKNOWN		0x0000ffff
+#define M3_BASELINE_VERSION		0x187
+#define M3_WAKE_SRC_MASK		0xFF
+#define M3_STATUS_RESP_MASK		(0xffff << 16)
+#define M3_FW_VERSION_MASK		0xffff
+
+#define M3_STATE_UNKNOWN		0
+#define M3_STATE_RESET			1
+#define M3_STATE_INITED			2
+#define M3_STATE_MSG_FOR_LP		3
+#define M3_STATE_MSG_FOR_RESET		4
+
+struct wkup_m3_wakeup_src {
+	int irq_nr;
+	char src[10];
+};
+
+struct wkup_m3_ipc {
+	struct rproc *rproc;
+
+	void __iomem *ipc_mem_base;
+	struct device *dev;
+
+	int mem_type;
+	unsigned long resume_addr;
+	int state;
+
+	struct mbox_client mbox_client;
+	struct mbox_chan *mbox;
+};
+
+static struct wkup_m3_ipc m3_ipc_state;
+
+static DECLARE_COMPLETION(m3_ipc_sync);
+
+static const struct wkup_m3_wakeup_src wakeups[] = {
+	{.irq_nr = 35,	.src = "USB0_PHY"},
+	{.irq_nr = 36,	.src = "USB1_PHY"},
+	{.irq_nr = 40,	.src = "I2C0"},
+	{.irq_nr = 41,	.src = "RTC Timer"},
+	{.irq_nr = 42,	.src = "RTC Alarm"},
+	{.irq_nr = 43,	.src = "Timer0"},
+	{.irq_nr = 44,	.src = "Timer1"},
+	{.irq_nr = 45,	.src = "UART"},
+	{.irq_nr = 46,	.src = "GPIO0"},
+	{.irq_nr = 48,	.src = "MPU_WAKE"},
+	{.irq_nr = 49,	.src = "WDT0"},
+	{.irq_nr = 50,	.src = "WDT1"},
+	{.irq_nr = 51,	.src = "ADC_TSC"},
+	{.irq_nr = 0,	.src = "Unknown"},
+};
+
+static inline void am33xx_txev_eoi(struct wkup_m3_ipc *m3_ipc)
+{
+	writel(AM33XX_M3_TXEV_ACK,
+	       m3_ipc->ipc_mem_base + AM33XX_CONTROL_M3_TXEV_EOI);
+}
+
+static inline void am33xx_txev_enable(struct wkup_m3_ipc *m3_ipc)
+{
+	writel(AM33XX_M3_TXEV_ENABLE,
+	       m3_ipc->ipc_mem_base + AM33XX_CONTROL_M3_TXEV_EOI);
+}
+
+static inline void wkup_m3_ctrl_ipc_write(struct wkup_m3_ipc *m3_ipc,
+					  u32 val, int ipc_reg_num)
+{
+	if (ipc_reg_num < 0 || ipc_reg_num > AM33XX_CTRL_IPC_REG_COUNT)
+		return;
+
+	writel(val, m3_ipc->ipc_mem_base +
+	       AM33XX_CTRL_IPC_REG_OFFSET(ipc_reg_num));
+}
+
+static inline unsigned int wkup_m3_ctrl_ipc_read(struct wkup_m3_ipc *m3_ipc,
+						 int ipc_reg_num)
+{
+	if (ipc_reg_num < 0 || ipc_reg_num > AM33XX_CTRL_IPC_REG_COUNT)
+		return 0;
+
+	return readl(m3_ipc->ipc_mem_base +
+		     AM33XX_CTRL_IPC_REG_OFFSET(ipc_reg_num));
+}
+
+static int wkup_m3_fw_version_read(void)
+{
+	int val;
+
+	val = wkup_m3_ctrl_ipc_read(&m3_ipc_state, 2);
+
+	return val & M3_FW_VERSION_MASK;
+}
+
+static irqreturn_t wkup_m3_txev_handler(int irq, void *ipc_data)
+{
+	struct wkup_m3_ipc *m3_ipc = (struct wkup_m3_ipc *)ipc_data;
+	struct device *dev = m3_ipc->dev;
+	int ver = 0;
+
+	am33xx_txev_eoi(m3_ipc);
+
+	switch (m3_ipc->state) {
+	case M3_STATE_RESET:
+		ver = wkup_m3_fw_version_read();
+
+		if (ver == M3_VERSION_UNKNOWN ||
+		    ver < M3_BASELINE_VERSION) {
+			dev_warn(dev, "CM3 Firmware Version %x not supported\n",
+				 ver);
+		} else {
+			dev_info(dev, "CM3 Firmware Version = 0x%x\n", ver);
+		}
+
+		m3_ipc->state = M3_STATE_INITED;
+		complete(&m3_ipc_sync);
+		break;
+	case M3_STATE_MSG_FOR_RESET:
+		m3_ipc->state = M3_STATE_INITED;
+		complete(&m3_ipc_sync);
+		break;
+	case M3_STATE_MSG_FOR_LP:
+		complete(&m3_ipc_sync);
+		break;
+	case M3_STATE_UNKNOWN:
+		dev_warn(dev, "Unknown CM3 State\n");
+	}
+
+	am33xx_txev_enable(m3_ipc);
+
+	return IRQ_HANDLED;
+}
+
+static void wkup_m3_mbox_callback(struct mbox_client *client, void *data)
+{
+	struct wkup_m3_ipc *m3_ipc = container_of(client, struct wkup_m3_ipc,
+						  mbox_client);
+
+	omap_mbox_disable_irq(m3_ipc->mbox, IRQ_RX);
+}
+
+static int wkup_m3_ping(void)
+{
+	struct device *dev = m3_ipc_state.dev;
+	mbox_msg_t dummy_msg = 0;
+	int ret;
+
+	if (!m3_ipc_state.mbox) {
+		dev_err(m3_ipc_state.dev,
+			"No IPC channel to communicate with wkup_m3!\n");
+		return -EIO;
+	}
+
+	/*
+	 * Write a dummy message to the mailbox in order to trigger the RX
+	 * interrupt to alert the M3 that data is available in the IPC
+	 * registers. We must enable the IRQ here and disable it after in
+	 * the RX callback to avoid multiple interrupts being received
+	 * by the CM3.
+	 */
+	omap_mbox_enable_irq(m3_ipc_state.mbox, IRQ_RX);
+	ret = mbox_send_message(m3_ipc_state.mbox, (void *)dummy_msg);
+	if (ret < 0) {
+		dev_err(dev, "%s: mbox_send_message() failed: %d\n",
+			__func__, ret);
+		return ret;
+	}
+
+	ret = wait_for_completion_timeout(&m3_ipc_sync,
+					  msecs_to_jiffies(500));
+	if (!ret) {
+		dev_err(dev, "MPU<->CM3 sync failure\n");
+		m3_ipc_state.state = M3_STATE_UNKNOWN;
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static const char *wkup_m3_request_wake_src(void)
+{
+	unsigned int wakeup_src_idx;
+	int j, val;
+
+	val = wkup_m3_ctrl_ipc_read(&m3_ipc_state, 6);
+
+	wakeup_src_idx = val & M3_WAKE_SRC_MASK;
+
+	for (j = 0; j < ARRAY_SIZE(wakeups)-1; j++) {
+		if (wakeups[j].irq_nr == wakeup_src_idx)
+			return wakeups[j].src;
+	}
+	return wakeups[j].src;
+}
+
+static int wkup_m3_is_available(void)
+{
+	return (m3_ipc_state.state != M3_STATE_RESET);
+}
+
+/* Public functions */
+/**
+ * wkup_m3_set_mem_type - Pass wkup_m3 which type of memory is in use
+ * @mem_type: memory type value read directly from emif
+ *
+ * wkup_m3 must know what memory type is in use to properly suspend
+ * and resume.
+ */
+void wkup_m3_set_mem_type(int mem_type)
+{
+	m3_ipc_state.mem_type = mem_type;
+}
+
+/**
+ * wkup_m3_set_resume_address - Pass wkup_m3 resume address
+ * @addr: Physical address from which resume code should execute
+ */
+void wkup_m3_set_resume_address(void *addr)
+{
+	m3_ipc_state.resume_addr = (unsigned long)addr;
+}
+
+/**
+ * wkup_m3_set_resume_address - Retrieve wkup_m3 status code after suspend
+ *
+ * Returns code representing the status of a low power mode transition.
+ *	0 - Successful transition
+ *	1 - Failure to transition to low power state
+ */
+int wkup_m3_request_pm_status(void)
+{
+	struct device *dev = m3_ipc_state.dev;
+	unsigned int i;
+	int val;
+	const char *wake_src;
+
+	/* print the wakeup reason */
+	wake_src = wkup_m3_request_wake_src();
+	dev_dbg(dev, "Wakeup source %s\n", wake_src);
+
+	val = wkup_m3_ctrl_ipc_read(&m3_ipc_state, 1);
+
+	i = M3_STATUS_RESP_MASK & val;
+	i >>= __ffs(M3_STATUS_RESP_MASK);
+
+	return i;
+}
+
+/**
+ * wkup_m3_prepare_low_power - Request preparation for transition to
+ *			       low power state
+ * @state: A kernel suspend state to enter, either MEM or STANDBY
+ *
+ * Returns 0 if preparation was successful, otherwise returns error code
+ */
+int wkup_m3_prepare_low_power(int state)
+{
+	struct device *dev = m3_ipc_state.dev;
+	int m3_power_state;
+	int ret = 0;
+
+	if (!wkup_m3_is_available()) {
+		dev_err(dev, "wkup_m3 not available. DeepSleep entry not possible.\n");
+		return -ENODEV;
+	}
+
+	switch (state) {
+	case PM_SUSPEND_MEM:
+		m3_power_state = IPC_CMD_DS0;
+		break;
+	default:
+		return 1;
+	}
+
+	/* Program each required IPC register then write defaults to others */
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, m3_ipc_state.resume_addr, 0);
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, m3_power_state, 1);
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, m3_ipc_state.mem_type, 4);
+
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, DS_IPC_DEFAULT, 2);
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, DS_IPC_DEFAULT, 3);
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, DS_IPC_DEFAULT, 5);
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, DS_IPC_DEFAULT, 6);
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, DS_IPC_DEFAULT, 7);
+
+	m3_ipc_state.state = M3_STATE_MSG_FOR_LP;
+
+	ret = wkup_m3_ping();
+	if (ret) {
+		dev_err(dev, "Unable to ping CM3\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * wkup_m3_finish_low_power - Return m3 to reset state
+ *
+ * Returns 0 if reset was successful, otherwise returns error code
+ */
+int wkup_m3_finish_low_power(void)
+{
+	struct device *dev = m3_ipc_state.dev;
+	int ret = 0;
+
+	if (!wkup_m3_is_available())
+		return -ENODEV;
+
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, IPC_CMD_RESET, 1);
+	wkup_m3_ctrl_ipc_write(&m3_ipc_state, DS_IPC_DEFAULT, 2);
+
+	m3_ipc_state.state = M3_STATE_MSG_FOR_RESET;
+
+	ret = wkup_m3_ping();
+	if (ret) {
+		dev_err(dev, "Unable to ping CM3\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int match(struct device *dev, void *data)
+{
+	struct device_node *node = (struct device_node *)data;
+
+	return dev->of_node == node;
+}
+
+static struct rproc *wkup_m3_get_rproc(struct device *dev)
+{
+	struct device_node *node;
+	struct rproc *rp;
+
+	node = of_parse_phandle(dev->of_node, "ti,rproc", 0);
+	if (!node)
+		return NULL;
+
+	dev = bus_find_device(&platform_bus_type, NULL, node, match);
+	if (!dev)
+		return NULL;
+
+	rp = dev_get_drvdata(dev);
+	return rp;
+}
+
+static void wkup_m3_rproc_boot_thread(struct rproc *rproc)
+{
+	struct device *dev = &rproc->dev;
+	int ret;
+
+	wait_for_completion(&rproc->firmware_loading_complete);
+
+	ret = rproc_boot(rproc);
+	if (ret)
+		dev_err(dev, "rproc_boot failed\n");
+
+	do_exit(0);
+}
+
+static int wkup_m3_ipc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	int irq, ret;
+	struct rproc *m3_rproc;
+	struct resource *res;
+	struct task_struct *task;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ipc_regs");
+	m3_ipc_state.ipc_mem_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(m3_ipc_state.ipc_mem_base)) {
+		dev_err(dev, "could not ioremap ipc_mem\n");
+		ret = PTR_ERR(m3_ipc_state.ipc_mem_base);
+		goto err;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (!irq) {
+		dev_err(&pdev->dev, "no irq resource\n");
+		ret = -ENXIO;
+		goto err;
+	}
+
+	ret = devm_request_irq(dev, irq, wkup_m3_txev_handler,
+			       IRQF_DISABLED, "wkup_m3_txev", &m3_ipc_state);
+	if (ret) {
+		dev_err(dev, "request_irq failed\n");
+		goto err;
+	}
+
+	m3_ipc_state.mbox_client.dev = dev;
+	m3_ipc_state.mbox_client.tx_done = NULL;
+	m3_ipc_state.mbox_client.rx_callback = wkup_m3_mbox_callback;
+	m3_ipc_state.mbox_client.tx_block = false;
+	m3_ipc_state.mbox_client.knows_txdone = false;
+
+	m3_ipc_state.mbox = mbox_request_channel(&m3_ipc_state.mbox_client, 0);
+	if (IS_ERR(m3_ipc_state.mbox)) {
+		dev_err(dev, "IPC Request for A8->M3 Channel failed! %ld\n",
+			PTR_ERR(m3_ipc_state.mbox));
+		ret = PTR_ERR(m3_ipc_state.mbox);
+		m3_ipc_state.mbox = NULL;
+		return ret;
+	}
+
+	m3_rproc = wkup_m3_get_rproc(dev);
+	if (!m3_rproc) {
+		ret = -EPROBE_DEFER;
+		goto err;
+	}
+
+	m3_ipc_state.dev = dev;
+	m3_ipc_state.state = M3_STATE_RESET;
+	/*
+	 * Wait for firmware loading completion in a thread so we
+	 * can boot the wkup_m3 as soon as it's ready without holding
+	 * up kernel boot
+	 */
+	task = kthread_run((void *)wkup_m3_rproc_boot_thread, m3_rproc,
+			   "wkup_m3_rproc_loader");
+
+	if (IS_ERR(task)) {
+		dev_err(dev, "can't create rproc_boot thread\n");
+		goto err;
+	}
+
+	return 0;
+
+err:
+	mbox_free_channel(m3_ipc_state.mbox);
+	return ret;
+}
+
+static int wkup_m3_ipc_remove(struct platform_device *pdev)
+{
+	if (m3_ipc_state.mbox)
+		mbox_free_channel(m3_ipc_state.mbox);
+
+	return 0;
+}
+
+static const struct of_device_id wkup_m3_ipc_of_match[] = {
+	{ .compatible = "ti,am3353-wkup-m3-ipc", .data = NULL, },
+	{},
+};
+
+static struct platform_driver wkup_m3_ipc_driver = {
+	.probe = wkup_m3_ipc_probe,
+	.remove = wkup_m3_ipc_remove,
+	.driver = {
+		.name = "wkup_m3_ipc",
+		.of_match_table = wkup_m3_ipc_of_match,
+	},
+};
+
+module_platform_driver(wkup_m3_ipc_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("wkup m3 remote processor ipc driver");
diff --git a/include/linux/wkup_m3_ipc.h b/include/linux/wkup_m3_ipc.h
new file mode 100644
index 0000000..a0c2722
--- /dev/null
+++ b/include/linux/wkup_m3_ipc.h
@@ -0,0 +1,33 @@
+/*
+ * TI Wakeup M3 for AMx3 SoCs Power Management Routines
+ *
+ * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
+ * Dave Gerlach <d-gerlach@xxxxxx>
+ *
+ * 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.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _LINUX_WKUP_M3_H
+#define _LINUX_WKUP_M3_H
+
+#ifdef CONFIG_WKUP_M3_IPC
+void wkup_m3_set_mem_type(int mem_type);
+void wkup_m3_set_resume_address(void *addr);
+int wkup_m3_prepare_low_power(int state);
+int wkup_m3_finish_low_power(void);
+int wkup_m3_request_pm_status(void);
+#else
+static inline void wkup_m3_set_mem_type(int mem_type) { }
+static inline void wkup_m3_set_resume_address(void *addr) { }
+static inline int wkup_m3_prepare_low_power(int state) { return -1; }
+static inline int wkup_m3_finish_low_power(void) { return -1; }
+static inline int wkup_m3_request_pm_status(void) { return -1; }
+#endif /* CONFIG_WKUP_M3_IPC */
+#endif /* _LINUX_WKUP_M3_H */
-- 
2.1.0

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