i2c: MPC8349E-mITX Power Management and GPIO expander driver

On MPC8349E-mITX, MPC8315E-RDB and MPC837x-RDB boards there is a
Freescale MC9S08QG8 (MCU) chip with the custom firmware
pre-programmed. The chip is used to power-off the board by the
software, and to control some GPIO pins.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

3 files changed, 221 insertions, 0 deletions

diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
index a95cb9465d65..17356827b93d 100644
--- a/drivers/i2c/chips/Kconfig
+++ b/drivers/i2c/chips/Kconfig
@@ -172,4 +172,15 @@ config MENELAUS
           and other features that are often used in portable devices like
           cell phones and PDAs.
 
+config MCU_MPC8349EMITX
+        tristate "MPC8349E-mITX MCU driver"
+        depends on I2C && PPC_83xx
+        select GENERIC_GPIO
+        select ARCH_REQUIRE_GPIOLIB
+        help
+          Say Y here to enable soft power-off functionality on the Freescale
+          boards with the MPC8349E-mITX-compatible MCU chips. This driver will
+          also register MCU GPIOs with the generic GPIO API, so you'll able
+          to use MCU pins as GPIOs.
+
 endmenu
diff --git a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile
index 39e3e69ed125..ca520fa143d6 100644
--- a/drivers/i2c/chips/Makefile
+++ b/drivers/i2c/chips/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_ISP1301_OMAP)	+= isp1301_omap.o
 obj-$(CONFIG_TPS65010)          += tps65010.o
 obj-$(CONFIG_MENELAUS)          += menelaus.o
 obj-$(CONFIG_SENSORS_TSL2550)   += tsl2550.o
+obj-$(CONFIG_MCU_MPC8349EMITX)  += mcu_mpc8349emitx.o
 
 ifeq ($(CONFIG_I2C_DEBUG_CHIP),y)
 EXTRA_CFLAGS += -DDEBUG
diff --git a/drivers/i2c/chips/mcu_mpc8349emitx.c b/drivers/i2c/chips/mcu_mpc8349emitx.c
new file mode 100644
index 000000000000..82a9bcb858b6
--- /dev/null
+++ b/drivers/i2c/chips/mcu_mpc8349emitx.c
@@ -0,0 +1,209 @@
+/*
+ * Power Management and GPIO expander driver for MPC8349E-mITX-compatible MCU
+ *
+ * Copyright (c) 2008  MontaVista Software, Inc.
+ *
+ * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/i2c.h>
+#include <linux/gpio.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <asm/prom.h>
+#include <asm/machdep.h>
+
+/*
+ * I don't have specifications for the MCU firmware, I found this register
+ * and bits positions by the trial&error method.
+ */
+#define MCU_REG_CTRL    0x20
+#define MCU_CTRL_POFF   0x40
+
+#define MCU_NUM_GPIO    2
+
+struct mcu {
+        struct mutex lock;
+        struct device_node *np;
+        struct i2c_client *client;
+        struct of_gpio_chip of_gc;
+        u8 reg_ctrl;
+};
+
+static struct mcu *glob_mcu;
+
+static void mcu_power_off(void)
+{
+        struct mcu *mcu = glob_mcu;
+
+        pr_info("Sending power-off request to the MCU...\n");
+        mutex_lock(&mcu->lock);
+        i2c_smbus_write_byte_data(glob_mcu->client, MCU_REG_CTRL,
+                                  mcu->reg_ctrl | MCU_CTRL_POFF);
+        mutex_unlock(&mcu->lock);
+}
+
+static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+        struct of_gpio_chip *of_gc = to_of_gpio_chip(gc);
+        struct mcu *mcu = container_of(of_gc, struct mcu, of_gc);
+        u8 bit = 1 << (4 + gpio);
+
+        mutex_lock(&mcu->lock);
+        if (val)
+                mcu->reg_ctrl &= ~bit;
+        else
+                mcu->reg_ctrl |= bit;
+
+        i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
+        mutex_unlock(&mcu->lock);
+}
+
+static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+        mcu_gpio_set(gc, gpio, val);
+        return 0;
+}
+
+static int mcu_gpiochip_add(struct mcu *mcu)
+{
+        struct device_node *np;
+        struct of_gpio_chip *of_gc = &mcu->of_gc;
+        struct gpio_chip *gc = &of_gc->gc;
+        int ret;
+
+        np = of_find_compatible_node(NULL, NULL, "fsl,mcu-mpc8349emitx");
+        if (!np)
+                return -ENODEV;
+
+        gc->owner = THIS_MODULE;
+        gc->label = np->full_name;
+        gc->can_sleep = 1;
+        gc->ngpio = MCU_NUM_GPIO;
+        gc->base = -1;
+        gc->set = mcu_gpio_set;
+        gc->direction_output = mcu_gpio_dir_out;
+        of_gc->gpio_cells = 2;
+        of_gc->xlate = of_gpio_simple_xlate;
+
+        np->data = of_gc;
+        mcu->np = np;
+
+        /*
+         * We don't want to lose the node, its ->data and ->full_name...
+         * So, if succeeded, we don't put the node here.
+         */
+        ret = gpiochip_add(gc);
+        if (ret)
+                of_node_put(np);
+        return ret;
+}
+
+static int mcu_gpiochip_remove(struct mcu *mcu)
+{
+        int ret;
+
+        ret = gpiochip_remove(&mcu->of_gc.gc);
+        if (ret)
+                return ret;
+        of_node_put(mcu->np);
+
+        return 0;
+}
+
+static int __devinit mcu_probe(struct i2c_client *client,
+                               const struct i2c_device_id *id)
+{
+        struct mcu *mcu;
+        int ret;
+
+        mcu = kzalloc(sizeof(*mcu), GFP_KERNEL);
+        if (!mcu)
+                return -ENOMEM;
+
+        mutex_init(&mcu->lock);
+        mcu->client = client;
+        i2c_set_clientdata(client, mcu);
+
+        ret = i2c_smbus_read_byte_data(mcu->client, MCU_REG_CTRL);
+        if (ret < 0)
+                goto err;
+        mcu->reg_ctrl = ret;
+
+        ret = mcu_gpiochip_add(mcu);
+        if (ret)
+                goto err;
+
+        /* XXX: this is potentially racy, but there is no lock for ppc_md */
+        if (!ppc_md.power_off) {
+                glob_mcu = mcu;
+                ppc_md.power_off = mcu_power_off;
+                dev_info(&client->dev, "will provide power-off service\n");
+        }
+
+        return 0;
+err:
+        kfree(mcu);
+        return ret;
+}
+
+static int __devexit mcu_remove(struct i2c_client *client)
+{
+        struct mcu *mcu = i2c_get_clientdata(client);
+        int ret;
+
+        if (glob_mcu == mcu) {
+                ppc_md.power_off = NULL;
+                glob_mcu = NULL;
+        }
+
+        ret = mcu_gpiochip_remove(mcu);
+        if (ret)
+                return ret;
+        i2c_set_clientdata(client, NULL);
+        kfree(mcu);
+        return 0;
+}
+
+static const struct i2c_device_id mcu_ids[] = {
+        { "mcu-mpc8349emitx", },
+        {},
+};
+MODULE_DEVICE_TABLE(i2c, mcu_ids);
+
+static struct i2c_driver mcu_driver = {
+        .driver = {
+                .name = "mcu-mpc8349emitx",
+                .owner = THIS_MODULE,
+        },
+        .probe = mcu_probe,
+        .remove = __devexit_p(mcu_remove),
+        .id_table = mcu_ids,
+};
+
+static int __init mcu_init(void)
+{
+        return i2c_add_driver(&mcu_driver);
+}
+module_init(mcu_init);
+
+static void __exit mcu_exit(void)
+{
+        i2c_del_driver(&mcu_driver);
+}
+module_exit(mcu_exit);
+
+MODULE_DESCRIPTION("Power Management and GPIO expander driver for "
+                   "MPC8349E-mITX-compatible MCU");
+MODULE_AUTHOR("Anton Vorontsov <avorontsov@ru.mvista.com>");
+MODULE_LICENSE("GPL");