spmi: Linux driver framework for SPMI

System Power Management Interface (SPMI) is a specification
developed by the MIPI (Mobile Industry Process Interface) Alliance
optimized for the real time control of Power Management ICs (PMIC).

SPMI is a two-wire serial interface that supports up to 4 master
devices and up to 16 logical slaves.

The framework supports message APIs, multiple busses (1 controller
per bus) and multiple clients/slave devices per controller.

Signed-off-by: Kenneth Heitke <kheitke@codeaurora.org>
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 622 insertions, 0 deletions

diff --git a/drivers/spmi/Kconfig b/drivers/spmi/Kconfig
new file mode 100644
index 0000000..1dbfee0
--- /dev/null
+++ b/drivers/spmi/Kconfig
@@ -0,0 +1,9 @@
+#
+# SPMI driver configuration
+#
+menuconfig SPMI
+	tristate "SPMI support"
+	help
+	  SPMI (System Power Management Interface) is a two-wire
+	  serial interface between baseband and application processors
+	  and Power Management Integrated Circuits (PMIC).
diff --git a/drivers/spmi/Makefile b/drivers/spmi/Makefile
new file mode 100644
index 0000000..1de1acd
--- /dev/null
+++ b/drivers/spmi/Makefile
@@ -0,0 +1,4 @@
+#
+# Makefile for kernel SPMI framework.
+#
+obj-$(CONFIG_SPMI)	+= spmi.o
diff --git a/drivers/spmi/spmi.c b/drivers/spmi/spmi.c
new file mode 100644
index 0000000..6122c8f
--- /dev/null
+++ b/drivers/spmi/spmi.c
@@ -0,0 +1,609 @@
+/* Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only 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/kernel.h>
+#include <linux/errno.h>
+#include <linux/idr.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/spmi.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+
+#include <dt-bindings/spmi/spmi.h>
+
+static DEFINE_IDA(ctrl_ida);
+
+static void spmi_dev_release(struct device *dev)
+{
+	struct spmi_device *sdev = to_spmi_device(dev);
+	kfree(sdev);
+}
+
+static const struct device_type spmi_dev_type = {
+	.release	= spmi_dev_release,
+};
+
+static void spmi_ctrl_release(struct device *dev)
+{
+	struct spmi_controller *ctrl = to_spmi_controller(dev);
+	ida_simple_remove(&ctrl_ida, ctrl->nr);
+	kfree(ctrl);
+}
+
+static const struct device_type spmi_ctrl_type = {
+	.release	= spmi_ctrl_release,
+};
+
+#ifdef CONFIG_PM_RUNTIME
+static int spmi_runtime_suspend(struct device *dev)
+{
+	struct spmi_device *sdev = to_spmi_device(dev);
+	int err;
+
+	err = pm_generic_runtime_suspend(dev);
+	if (err)
+		return err;
+
+	return spmi_command_sleep(sdev);
+}
+
+static int spmi_runtime_resume(struct device *dev)
+{
+	struct spmi_device *sdev = to_spmi_device(dev);
+	int err;
+
+	err = spmi_command_wakeup(sdev);
+	if (err)
+		return err;
+
+	return pm_generic_runtime_resume(dev);
+}
+#endif
+
+static const struct dev_pm_ops spmi_pm_ops = {
+	SET_RUNTIME_PM_OPS(
+		spmi_runtime_suspend,
+		spmi_runtime_resume,
+		NULL
+	)
+};
+
+static int spmi_device_match(struct device *dev, struct device_driver *drv)
+{
+	if (of_driver_match_device(dev, drv))
+		return 1;
+
+	if (drv->name)
+		return strncmp(dev_name(dev), drv->name,
+			       SPMI_NAME_SIZE) == 0;
+
+	return 0;
+}
+
+/**
+ * spmi_device_add() - add a device previously constructed via spmi_device_alloc()
+ * @sdev:	spmi_device to be added
+ */
+int spmi_device_add(struct spmi_device *sdev)
+{
+	struct spmi_controller *ctrl = sdev->ctrl;
+	int err;
+
+	dev_set_name(&sdev->dev, "%d-%02x", ctrl->nr, sdev->usid);
+
+	err = device_add(&sdev->dev);
+	if (err < 0) {
+		dev_err(&sdev->dev, "Can't add %s, status %d\n",
+			dev_name(&sdev->dev), err);
+		goto err_device_add;
+	}
+
+	dev_dbg(&sdev->dev, "device %s registered\n", dev_name(&sdev->dev));
+
+err_device_add:
+	return err;
+}
+EXPORT_SYMBOL_GPL(spmi_device_add);
+
+/**
+ * spmi_device_remove(): remove an SPMI device
+ * @sdev:	spmi_device to be removed
+ */
+void spmi_device_remove(struct spmi_device *sdev)
+{
+	device_unregister(&sdev->dev);
+}
+EXPORT_SYMBOL_GPL(spmi_device_remove);
+
+static inline int
+spmi_cmd(struct spmi_controller *ctrl, u8 opcode, u8 sid)
+{
+	if (!ctrl || !ctrl->cmd || ctrl->dev.type != &spmi_ctrl_type)
+		return -EINVAL;
+
+	return ctrl->cmd(ctrl, opcode, sid);
+}
+
+static inline int spmi_read_cmd(struct spmi_controller *ctrl, u8 opcode,
+				u8 sid, u16 addr, u8 *buf, size_t len)
+{
+	if (!ctrl || !ctrl->read_cmd || ctrl->dev.type != &spmi_ctrl_type)
+		return -EINVAL;
+
+	return ctrl->read_cmd(ctrl, opcode, sid, addr, buf, len);
+}
+
+static inline int spmi_write_cmd(struct spmi_controller *ctrl, u8 opcode,
+				 u8 sid, u16 addr, const u8 *buf, size_t len)
+{
+	if (!ctrl || !ctrl->write_cmd || ctrl->dev.type != &spmi_ctrl_type)
+		return -EINVAL;
+
+	return ctrl->write_cmd(ctrl, opcode, sid, addr, buf, len);
+}
+
+/**
+ * spmi_register_read() - register read
+ * @sdev:	SPMI device.
+ * @addr:	slave register address (5-bit address).
+ * @buf:	buffer to be populated with data from the Slave.
+ *
+ * Reads 1 byte of data from a Slave device register.
+ */
+int spmi_register_read(struct spmi_device *sdev, u8 addr, u8 *buf)
+{
+	/* 5-bit register address */
+	if (addr > 0x1F)
+		return -EINVAL;
+
+	return spmi_read_cmd(sdev->ctrl, SPMI_CMD_READ, sdev->usid, addr,
+			     buf, 1);
+}
+EXPORT_SYMBOL_GPL(spmi_register_read);
+
+/**
+ * spmi_ext_register_read() - extended register read
+ * @sdev:	SPMI device.
+ * @addr:	slave register address (8-bit address).
+ * @buf:	buffer to be populated with data from the Slave.
+ * @len:	the request number of bytes to read (up to 16 bytes).
+ *
+ * Reads up to 16 bytes of data from the extended register space on a
+ * Slave device.
+ */
+int spmi_ext_register_read(struct spmi_device *sdev, u8 addr, u8 *buf,
+			   size_t len)
+{
+	/* 8-bit register address, up to 16 bytes */
+	if (len == 0 || len > 16)
+		return -EINVAL;
+
+	return spmi_read_cmd(sdev->ctrl, SPMI_CMD_EXT_READ, sdev->usid, addr,
+			     buf, len);
+}
+EXPORT_SYMBOL_GPL(spmi_ext_register_read);
+
+/**
+ * spmi_ext_register_readl() - extended register read long
+ * @sdev:	SPMI device.
+ * @addr:	slave register address (16-bit address).
+ * @buf:	buffer to be populated with data from the Slave.
+ * @len:	the request number of bytes to read (up to 8 bytes).
+ *
+ * Reads up to 8 bytes of data from the extended register space on a
+ * Slave device using 16-bit address.
+ */
+int spmi_ext_register_readl(struct spmi_device *sdev, u16 addr, u8 *buf,
+			    size_t len)
+{
+	/* 16-bit register address, up to 8 bytes */
+	if (len == 0 || len > 8)
+		return -EINVAL;
+
+	return spmi_read_cmd(sdev->ctrl, SPMI_CMD_EXT_READL, sdev->usid, addr,
+			     buf, len);
+}
+EXPORT_SYMBOL_GPL(spmi_ext_register_readl);
+
+/**
+ * spmi_register_write() - register write
+ * @sdev:	SPMI device
+ * @addr:	slave register address (5-bit address).
+ * @data:	buffer containing the data to be transferred to the Slave.
+ *
+ * Writes 1 byte of data to a Slave device register.
+ */
+int spmi_register_write(struct spmi_device *sdev, u8 addr, u8 data)
+{
+	/* 5-bit register address */
+	if (addr > 0x1F)
+		return -EINVAL;
+
+	return spmi_write_cmd(sdev->ctrl, SPMI_CMD_WRITE, sdev->usid, addr,
+			      &data, 1);
+}
+EXPORT_SYMBOL_GPL(spmi_register_write);
+
+/**
+ * spmi_register_zero_write() - register zero write
+ * @sdev:	SPMI device.
+ * @data:	the data to be written to register 0 (7-bits).
+ *
+ * Writes data to register 0 of the Slave device.
+ */
+int spmi_register_zero_write(struct spmi_device *sdev, u8 data)
+{
+	return spmi_write_cmd(sdev->ctrl, SPMI_CMD_ZERO_WRITE, sdev->usid, 0,
+			      &data, 1);
+}
+EXPORT_SYMBOL_GPL(spmi_register_zero_write);
+
+/**
+ * spmi_ext_register_write() - extended register write
+ * @sdev:	SPMI device.
+ * @addr:	slave register address (8-bit address).
+ * @buf:	buffer containing the data to be transferred to the Slave.
+ * @len:	the request number of bytes to read (up to 16 bytes).
+ *
+ * Writes up to 16 bytes of data to the extended register space of a
+ * Slave device.
+ */
+int spmi_ext_register_write(struct spmi_device *sdev, u8 addr, const u8 *buf,
+			    size_t len)
+{
+	/* 8-bit register address, up to 16 bytes */
+	if (len == 0 || len > 16)
+		return -EINVAL;
+
+	return spmi_write_cmd(sdev->ctrl, SPMI_CMD_EXT_WRITE, sdev->usid, addr,
+			      buf, len);
+}
+EXPORT_SYMBOL_GPL(spmi_ext_register_write);
+
+/**
+ * spmi_ext_register_writel() - extended register write long
+ * @sdev:	SPMI device.
+ * @addr:	slave register address (16-bit address).
+ * @buf:	buffer containing the data to be transferred to the Slave.
+ * @len:	the request number of bytes to read (up to 8 bytes).
+ *
+ * Writes up to 8 bytes of data to the extended register space of a
+ * Slave device using 16-bit address.
+ */
+int spmi_ext_register_writel(struct spmi_device *sdev, u16 addr, const u8 *buf,
+			     size_t len)
+{
+	/* 4-bit Slave Identifier, 16-bit register address, up to 8 bytes */
+	if (len == 0 || len > 8)
+		return -EINVAL;
+
+	return spmi_write_cmd(sdev->ctrl, SPMI_CMD_EXT_WRITEL, sdev->usid,
+			      addr, buf, len);
+}
+EXPORT_SYMBOL_GPL(spmi_ext_register_writel);
+
+/**
+ * spmi_command_reset() - sends RESET command to the specified slave
+ * @sdev:	SPMI device.
+ *
+ * The Reset command initializes the Slave and forces all registers to
+ * their reset values. The Slave shall enter the STARTUP state after
+ * receiving a Reset command.
+ */
+int spmi_command_reset(struct spmi_device *sdev)
+{
+	return spmi_cmd(sdev->ctrl, SPMI_CMD_RESET, sdev->usid);
+}
+EXPORT_SYMBOL_GPL(spmi_command_reset);
+
+/**
+ * spmi_command_sleep() - sends SLEEP command to the specified SPMI device
+ * @sdev:	SPMI device.
+ *
+ * The Sleep command causes the Slave to enter the user defined SLEEP state.
+ */
+int spmi_command_sleep(struct spmi_device *sdev)
+{
+	return spmi_cmd(sdev->ctrl, SPMI_CMD_SLEEP, sdev->usid);
+}
+EXPORT_SYMBOL_GPL(spmi_command_sleep);
+
+/**
+ * spmi_command_wakeup() - sends WAKEUP command to the specified SPMI device
+ * @sdev:	SPMI device.
+ *
+ * The Wakeup command causes the Slave to move from the SLEEP state to
+ * the ACTIVE state.
+ */
+int spmi_command_wakeup(struct spmi_device *sdev)
+{
+	return spmi_cmd(sdev->ctrl, SPMI_CMD_WAKEUP, sdev->usid);
+}
+EXPORT_SYMBOL_GPL(spmi_command_wakeup);
+
+/**
+ * spmi_command_shutdown() - sends SHUTDOWN command to the specified SPMI device
+ * @sdev:	SPMI device.
+ *
+ * The Shutdown command causes the Slave to enter the SHUTDOWN state.
+ */
+int spmi_command_shutdown(struct spmi_device *sdev)
+{
+	return spmi_cmd(sdev->ctrl, SPMI_CMD_SHUTDOWN, sdev->usid);
+}
+EXPORT_SYMBOL_GPL(spmi_command_shutdown);
+
+static int spmi_drv_probe(struct device *dev)
+{
+	const struct spmi_driver *sdrv = to_spmi_driver(dev->driver);
+	struct spmi_device *sdev = to_spmi_device(dev);
+	int err;
+
+	/* Ensure the slave is in ACTIVE state */
+	err = spmi_command_wakeup(sdev);
+	if (err)
+		goto fail_wakeup;
+
+	pm_runtime_get_noresume(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
+	err = sdrv->probe(sdev);
+	if (err)
+		goto fail_probe;
+
+	return 0;
+
+fail_probe:
+	pm_runtime_disable(dev);
+	pm_runtime_set_suspended(dev);
+	pm_runtime_put_noidle(dev);
+fail_wakeup:
+	return err;
+}
+
+static int spmi_drv_remove(struct device *dev)
+{
+	const struct spmi_driver *sdrv = to_spmi_driver(dev->driver);
+
+	pm_runtime_get_sync(dev);
+	sdrv->remove(to_spmi_device(dev));
+	pm_runtime_put_noidle(dev);
+
+	pm_runtime_disable(dev);
+	pm_runtime_set_suspended(dev);
+	pm_runtime_put_noidle(dev);
+	return 0;
+}
+
+static struct bus_type spmi_bus_type = {
+	.name		= "spmi",
+	.match		= spmi_device_match,
+	.pm		= &spmi_pm_ops,
+	.probe		= spmi_drv_probe,
+	.remove		= spmi_drv_remove,
+};
+
+/**
+ * spmi_controller_alloc() - Allocate a new SPMI device
+ * @ctrl:	associated controller
+ *
+ * Caller is responsible for either calling spmi_device_add() to add the
+ * newly allocated controller, or calling spmi_device_put() to discard it.
+ */
+struct spmi_device *spmi_device_alloc(struct spmi_controller *ctrl)
+{
+	struct spmi_device *sdev;
+
+	sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
+	if (!sdev)
+		return NULL;
+
+	sdev->ctrl = ctrl;
+	device_initialize(&sdev->dev);
+	sdev->dev.parent = &ctrl->dev;
+	sdev->dev.bus = &spmi_bus_type;
+	sdev->dev.type = &spmi_dev_type;
+	return sdev;
+}
+EXPORT_SYMBOL_GPL(spmi_device_alloc);
+
+/**
+ * spmi_controller_alloc() - Allocate a new SPMI controller
+ * @parent:	parent device
+ * @size:	size of private data
+ *
+ * Caller is responsible for either calling spmi_controller_add() to add the
+ * newly allocated controller, or calling spmi_controller_put() to discard it.
+ * The allocated private data region may be accessed via
+ * spmi_controller_get_drvdata()
+ */
+struct spmi_controller *spmi_controller_alloc(struct device *parent,
+					      size_t size)
+{
+	struct spmi_controller *ctrl;
+	int id;
+
+	if (WARN_ON(!parent))
+		return NULL;
+
+	ctrl = kzalloc(sizeof(*ctrl) + size, GFP_KERNEL);
+	if (!ctrl)
+		return NULL;
+
+	device_initialize(&ctrl->dev);
+	ctrl->dev.type = &spmi_ctrl_type;
+	ctrl->dev.bus = &spmi_bus_type;
+	ctrl->dev.parent = parent;
+	ctrl->dev.of_node = parent->of_node;
+	spmi_controller_set_drvdata(ctrl, &ctrl[1]);
+
+	id = ida_simple_get(&ctrl_ida, 0, 0, GFP_KERNEL);
+	if (id < 0) {
+		dev_err(parent,
+			"unable to allocate SPMI controller identifier.\n");
+		spmi_controller_put(ctrl);
+		return NULL;
+	}
+
+	ctrl->nr = id;
+	dev_set_name(&ctrl->dev, "spmi-%d", id);
+
+	dev_dbg(&ctrl->dev, "allocated controller 0x%p id %d\n", ctrl, id);
+	return ctrl;
+}
+EXPORT_SYMBOL_GPL(spmi_controller_alloc);
+
+static void of_spmi_register_devices(struct spmi_controller *ctrl)
+{
+	struct device_node *node;
+	int err;
+
+	if (!ctrl->dev.of_node)
+		return;
+
+	for_each_available_child_of_node(ctrl->dev.of_node, node) {
+		struct spmi_device *sdev;
+		u32 reg[2];
+
+		dev_dbg(&ctrl->dev, "adding child %s\n", node->full_name);
+
+		err = of_property_read_u32_array(node, "reg", reg, 2);
+		if (err) {
+			dev_err(&ctrl->dev,
+				"node %s err (%d) does not have 'reg' property\n",
+				node->full_name, err);
+			continue;
+		}
+
+		if (reg[1] != SPMI_USID) {
+			dev_err(&ctrl->dev,
+				"node %s contains unsupported 'reg' entry\n",
+				node->full_name);
+			continue;
+		}
+
+		if (reg[0] >= SPMI_MAX_SLAVE_ID) {
+			dev_err(&ctrl->dev,
+				"invalid usid on node %s\n",
+				node->full_name);
+			continue;
+		}
+
+		dev_dbg(&ctrl->dev, "read usid %02x\n", reg[0]);
+
+		sdev = spmi_device_alloc(ctrl);
+		if (!sdev)
+			continue;
+
+		sdev->dev.of_node = node;
+		sdev->usid = (u8) reg[0];
+
+		err = spmi_device_add(sdev);
+		if (err) {
+			dev_err(&sdev->dev,
+				"failure adding device. status %d\n", err);
+			spmi_device_put(sdev);
+		}
+	}
+}
+
+/**
+ * spmi_controller_add() - Add an SPMI controller
+ * @ctrl:	controller to be registered.
+ *
+ * Register a controller previously allocated via spmi_controller_alloc() with
+ * the SPMI core.
+ */
+int spmi_controller_add(struct spmi_controller *ctrl)
+{
+	int ret;
+
+	/* Can't register until after driver model init */
+	if (WARN_ON(!spmi_bus_type.p))
+		return -EAGAIN;
+
+	ret = device_add(&ctrl->dev);
+	if (ret)
+		return ret;
+
+	if (IS_ENABLED(CONFIG_OF))
+		of_spmi_register_devices(ctrl);
+
+	dev_dbg(&ctrl->dev, "spmi-%d registered: dev:%p\n",
+		ctrl->nr, &ctrl->dev);
+
+	return 0;
+};
+EXPORT_SYMBOL_GPL(spmi_controller_add);
+
+/* Remove a device associated with a controller */
+static int spmi_ctrl_remove_device(struct device *dev, void *data)
+{
+	struct spmi_device *spmidev = to_spmi_device(dev);
+	if (dev->type == &spmi_dev_type)
+		spmi_device_remove(spmidev);
+	return 0;
+}
+
+/**
+ * spmi_controller_remove(): remove an SPMI controller
+ * @ctrl:	controller to remove
+ *
+ * Remove a SPMI controller.  Caller is responsible for calling
+ * spmi_controller_put() to discard the allocated controller.
+ */
+void spmi_controller_remove(struct spmi_controller *ctrl)
+{
+	int dummy;
+
+	if (!ctrl)
+		return;
+
+	dummy = device_for_each_child(&ctrl->dev, NULL,
+				      spmi_ctrl_remove_device);
+	device_del(&ctrl->dev);
+}
+EXPORT_SYMBOL_GPL(spmi_controller_remove);
+
+/**
+ * spmi_driver_register() - Register client driver with SPMI core
+ * @sdrv:	client driver to be associated with client-device.
+ *
+ * This API will register the client driver with the SPMI framework.
+ * It is typically called from the driver's module-init function.
+ */
+int spmi_driver_register(struct spmi_driver *sdrv)
+{
+	sdrv->driver.bus = &spmi_bus_type;
+	return driver_register(&sdrv->driver);
+}
+EXPORT_SYMBOL_GPL(spmi_driver_register);
+
+static void __exit spmi_exit(void)
+{
+	bus_unregister(&spmi_bus_type);
+}
+module_exit(spmi_exit);
+
+static int __init spmi_init(void)
+{
+	return bus_register(&spmi_bus_type);
+}
+postcore_initcall(spmi_init);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("SPMI module");
+MODULE_ALIAS("platform:spmi");