[2/2] 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>

On Fri, Sep 19, 2008 at 10:03:54PM +0400, Anton Vorontsov wrote:
> 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.

I suppose there's no other place for this sort of thing to go at
the moment other than drivers/i2c/chips.

I've also a driver for a similar PMU fitted to a number
of our boards that provides basic gpio (wakeup sources) and some
minimalist power management (so isn't really fit for regulator
framwork) and isn't really a gpio chip (so drivers/gpio isn't
really the place for it either.)
 
> Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
> ---
>  drivers/i2c/chips/Kconfig            |   11 ++
>  drivers/i2c/chips/Makefile           |    1 +
>  drivers/i2c/chips/mcu_mpc8349emitx.c |  213 ++++++++++++++++++++++++++++++++++
>  3 files changed, 225 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/i2c/chips/mcu_mpc8349emitx.c
> 
> diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
> index a95cb94..1735682 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 39e3e69..ca520fa 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 0000000..47b07b8
> --- /dev/null
> +++ b/drivers/i2c/chips/mcu_mpc8349emitx.c
> @@ -0,0 +1,213 @@
> +/*
> + * 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[] = {
> +	{ "mc9s08qg8-mpc8349emitx", },
> +	{ "mc9s08qg8-mpc8377rdb", },
> +	{ "mc9s08qg8-mpc8378rdb", },
> +	{ "mc9s08qg8-mpc8379rdb", },
> +	{ "mc9s08qg8-mpc8315rdb", },
> +	{},
> +};
> +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");
> -- 
> 1.5.6.3
> 
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> i2c@lm-sensors.org
> http://lists.lm-sensors.org/mailman/listinfo/i2c

On Mon, Sep 22, 2008 at 11:45:40PM +0100, Ben Dooks wrote:

> I've also a driver for a similar PMU fitted to a number
> of our boards that provides basic gpio (wakeup sources) and some
> minimalist power management (so isn't really fit for regulator
> framwork) and isn't really a gpio chip (so drivers/gpio isn't
> really the place for it either.)

FWIW the regulator framework does have support for representing things
as limited as completely non-controllable regulators so it may still be
worth considering that.  It at least provides a degree of abstraction
for the clients in case they are used with more complex regulators and
would allow integration of your PMU with more complex secondary
regulators.  May not be worth the bother, though.