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Date:	Fri, 16 Mar 2012 20:01:56 -0700
From:	Guenter Roeck <guenter.roeck@...csson.com>
To:	Diego Elio Pettenò <flameeyes@...meeyes.eu>
CC:	linux-kernel@...r.kernel.org,
	Grant Likely <grant.likely@...retlab.ca>,
	Linus Walleij <linus.walleij@...ricsson.com>
Subject: Re: [PATCH] gpio: add support for ITE IT87xx Super I/O GPIO.

On Fri, Mar 16, 2012 at 08:48:13PM +0100, Diego Elio Pettenò wrote:
> The driver is currently written for IT8728, but the code in it87_wdt
> suggest it would work the same way on many other versions.
> 

The it87 hwmon driver accesses superio registers only during initialization,
so the risk for conflicts is quite low. Seems to me that is not the case here.

Maybe about time to convert the drivers to use the mfd infrastructure.
Hope that won't require datasheets for their recent chips, as close-lipped
as ITD is about those lately.

Guenter

> This is just a first step to verify the working status of the code,
> and might require moving to a MFD approach to share with hwmon/it87
> and it87_wdt, as they all share the same access to the Super I/O chip.
> That would also allow to set a few more opitons so that you could for
> instance change the function selection of a few pins from their
> default to GPIO pins.
> 
> It does not yet support the polarity-inversion register that is
> allowed by the chipset, which might require sysfs attributes per-gpio.
> 
> CC: Grant Likely <grant.likely@...retlab.ca>
> CC: Linus Walleij <linus.walleij@...ricsson.com>
> Signed-off-by: Diego Elio Pettenò <flameeyes@...meeyes.eu>
> ---
>  MAINTAINERS              |    5 +
>  drivers/gpio/Kconfig     |   11 ++
>  drivers/gpio/Makefile    |    1 +
>  drivers/gpio/gpio-it87.c |  397 ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 414 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/gpio/gpio-it87.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 553ac10..a196f14 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3692,6 +3692,11 @@ S:	Maintained
>  F:	Documentation/hwmon/it87
>  F:	drivers/hwmon/it87.c
>  
> +IT87xx GPIO DRIVER
> +M:	Diego Elio Pettenò <flameeyes@...meeyes.eu>
> +S:	Maintained
> +F:	drivers/gpio/gpio-it87.c
> +
>  IVTV VIDEO4LINUX DRIVER
>  M:	Andy Walls <awalls@...metrocast.net>
>  L:	ivtv-devel@...vdriver.org (moderated for non-subscribers)
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 3359f1e..8dc26b7 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -91,6 +91,17 @@ config GPIO_IT8761E
>  	help
>  	  Say yes here to support GPIO functionality of IT8761E super I/O chip.
>  
> +config GPIO_IT87
> +	tristate "IT87xx GPIO support"
> +	depends on X86 # unconditional access to IO space.
> +	help
> +	  Say yes here to support GPIO functionality of IT87xx Super I/O chips.
> +
> +	  This driver currently supports ITE IT8728 Super I/O chips.
> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called gpio_it87
> +
>  config GPIO_EP93XX
>  	def_bool y
>  	depends on ARCH_EP93XX
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 41fe67f..affe510 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -18,6 +18,7 @@ obj-$(CONFIG_ARCH_DAVINCI)	+= gpio-davinci.o
>  obj-$(CONFIG_GPIO_EP93XX)	+= gpio-ep93xx.o
>  obj-$(CONFIG_GPIO_ICH)		+= gpio-ich.o
>  obj-$(CONFIG_GPIO_IT8761E)	+= gpio-it8761e.o
> +obj-$(CONFIG_GPIO_IT87)		+= gpio-it87.o
>  obj-$(CONFIG_GPIO_JANZ_TTL)	+= gpio-janz-ttl.o
>  obj-$(CONFIG_ARCH_KS8695)	+= gpio-ks8695.o
>  obj-$(CONFIG_GPIO_LANGWELL)	+= gpio-langwell.o
> diff --git a/drivers/gpio/gpio-it87.c b/drivers/gpio/gpio-it87.c
> new file mode 100644
> index 0000000..958c126
> --- /dev/null
> +++ b/drivers/gpio/gpio-it87.c
> @@ -0,0 +1,397 @@
> +/*
> + *  GPIO interface for IT87xx Super I/O chips
> + *
> + *  Author: Diego Elio Pettenò <flameeyes@...meeyes.eu>
> + *
> + *  Based on it87_wdt.c     by Oliver Schuster
> + *           gpio-it8761e.c by Denis Turischev
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License 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.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; see the file COPYING.  If not, write to
> + *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/errno.h>
> +#include <linux/ioport.h>
> +
> +#include <linux/gpio.h>
> +
> +#define GPIO_NAME "it87-gpio"
> +#define PFX GPIO_NAME ": "
> +
> +/* Chip Id numbers */
> +#define NO_DEV_ID	0xffff
> +#define IT8728_ID	0x8728
> +
> +/* IO Ports */
> +#define REG		0x2e
> +#define VAL		0x2f
> +
> +/* Logical device Numbers LDN */
> +#define GPIO		0x07
> +
> +/* Configuration Registers and Functions */
> +#define LDNREG		0x07
> +#define CHIPID		0x20
> +#define CHIPREV		0x22
> +
> +/* GPIO Simple I/O Base Address registers */
> +#define GPIO_BASE	0x62
> +#define GPIO_IOSIZE	8
> +
> +/* GPIO polarity inverting registers base */
> +#define GPIO_PS_BASE	0xb0 /* to 0xb4 */
> +/* Simple I/O Enable registers base */
> +#define GPIO_SE_BASE	0xc0 /* to 0xc4 */
> +#define GPIO_SE_SIZE	5
> +/* Output Enable registers base */
> +#define GPIO_OE_BASE	0xc8 /* to 0xcf */
> +
> +/* Superio Chip */
> +
> +static inline int superio_enter(void)
> +{
> +	/*
> +	 * Try to reserve REG and REG + 1 for exclusive access.
> +	 */
> +	if (!request_muxed_region(REG, 2, GPIO_NAME))
> +		return -EBUSY;
> +
> +	outb(0x87, REG);
> +	outb(0x01, REG);
> +	outb(0x55, REG);
> +	outb(0x55, REG);
> +	return 0;
> +}
> +
> +static inline void superio_exit(void)
> +{
> +	outb(0x02, REG);
> +	outb(0x02, VAL);
> +	release_region(REG, 2);
> +}
> +
> +static inline void superio_select(int ldn)
> +{
> +	outb(LDNREG, REG);
> +	outb(ldn, VAL);
> +}
> +
> +static inline int superio_inb(int reg)
> +{
> +	outb(reg, REG);
> +	return inb(VAL);
> +}
> +
> +static inline void superio_outb(int val, int reg)
> +{
> +	outb(reg, REG);
> +	outb(val, VAL);
> +}
> +
> +static inline int superio_inw(int reg)
> +{
> +	int val;
> +	outb(reg++, REG);
> +	val = inb(VAL) << 8;
> +	outb(reg, REG);
> +	val |= inb(VAL);
> +	return val;
> +}
> +
> +static inline void superio_outw(int val, int reg)
> +{
> +	outb(reg++, REG);
> +	outb(val >> 8, VAL);
> +	outb(reg, REG);
> +	outb(val, VAL);
> +}
> +
> +static inline void superio_set_bit(int bit, int reg)
> +{
> +	u8 curr_val = superio_inb(reg);
> +	u8 new_val = curr_val | 1 << bit;
> +
> +	if (curr_val != new_val)
> +		superio_outb(new_val, reg);
> +}
> +
> +static inline void superio_clear_bit(int bit, int reg)
> +{
> +	u8 curr_val = superio_inb(reg);
> +	u8 new_val = curr_val & ~(1 << bit);
> +
> +	if (curr_val != new_val)
> +		superio_outb(new_val, reg);
> +}
> +
> +static u16 gpio_ba;
> +
> +static int it87_gpio_request(struct gpio_chip *gc, unsigned gpio_num)
> +{
> +	u8 bit, group;
> +	int rc;
> +
> +	bit = gpio_num % 8;
> +	group = (gpio_num / 8);
> +
> +	if ((rc = superio_enter()))
> +		return rc;
> +
> +	/* enable Simple I/O on the GPIO pin, removing alternate
> +	 * function; only the first five groups are programmable as
> +	 * either Simple I/O or alternate function, the final free are
> +	 * always set to Simple I/O.
> +	 *
> +	 * This might differ depending on chip type so it could have
> +	 * to be made configurable.
> +	 */
> +	if (group >= GPIO_SE_SIZE)
> +		superio_set_bit(bit, group + GPIO_SE_BASE);
> +
> +	/* clear output enable, setting the pin to input, as all the
> +	 * newly-exported GPIO interfaces are set to input.
> +	 */
> +	superio_clear_bit(bit, group + GPIO_OE_BASE);
> +
> +	superio_exit();
> +
> +	return 0;
> +}
> +
> +static int it87_gpio_get(struct gpio_chip *gc, unsigned gpio_num)
> +{
> +	u16 reg;
> +	u8 bit;
> +
> +	bit = gpio_num % 8;
> +	reg = (gpio_num / 8) + gpio_ba;
> +
> +	return !!(inb(reg) & (1 << bit));
> +}
> +
> +static int it87_gpio_direction_in(struct gpio_chip *gc, unsigned gpio_num)
> +{
> +	u8 bit, group;
> +	int rc;
> +
> +	bit = gpio_num % 8;
> +	group = (gpio_num / 8);
> +
> +	if ((rc = superio_enter()))
> +		return rc;
> +
> +	/* clear the output enable bit */
> +	superio_clear_bit(bit, group + GPIO_OE_BASE);
> +
> +	superio_exit();
> +
> +	return 0;
> +}
> +
> +static void it87_gpio_set(struct gpio_chip *gc,
> +			  unsigned gpio_num, int val)
> +{
> +	unsigned long flags;
> +	u8 curr_vals, bit;
> +	u16 reg;
> +
> +	bit = gpio_num % 8;
> +	reg = (gpio_num / 8) + gpio_ba;
> +
> +	curr_vals = inb(reg);
> +	if (val)
> +		outb(curr_vals | (1 << bit) , reg);
> +	else
> +		outb(curr_vals & ~(1 << bit), reg);
> +}
> +
> +static int it87_gpio_direction_out(struct gpio_chip *gc,
> +				   unsigned gpio_num, int val)
> +{
> +	u8 bit, group;
> +	int rc;
> +
> +	bit = gpio_num % 8;
> +	group = (gpio_num / 8);
> +
> +	if ((rc = superio_enter()))
> +		return rc;
> +
> +	/* set the output enable bit */
> +	superio_set_bit(bit, group + GPIO_OE_BASE);
> +
> +	it87_gpio_set(gc, gpio_num, val);
> +
> +	superio_exit();
> +
> +	return 0;
> +}
> +
> +/* ITE documentation refers to the GPIO registers as coordinates of
> + * group/bit; we alias them as otherwise it becomes hard to find a
> + * correlation between the chip's offsets and the names in the
> + * documentation.
> + */
> +static const char *const it87_gpio_aliases[] = {
> +	"it87_gp10",
> +	"it87_gp11",
> +	"it87_gp12",
> +	"it87_gp13",
> +	"it87_gp14",
> +	"it87_gp15",
> +	"it87_gp16",
> +	"it87_gp17",
> +	"it87_gp20",
> +	"it87_gp21",
> +	"it87_gp22",
> +	"it87_gp23",
> +	"it87_gp24",
> +	"it87_gp25",
> +	"it87_gp26",
> +	"it87_gp27",
> +	"it87_gp30",
> +	"it87_gp31",
> +	"it87_gp32",
> +	"it87_gp33",
> +	"it87_gp34",
> +	"it87_gp35",
> +	"it87_gp36",
> +	"it87_gp37",
> +	"it87_gp40",
> +	"it87_gp41",
> +	"it87_gp42",
> +	"it87_gp43",
> +	"it87_gp44",
> +	"it87_gp45",
> +	"it87_gp46",
> +	"it87_gp47",
> +	"it87_gp50",
> +	"it87_gp51",
> +	"it87_gp52",
> +	"it87_gp53",
> +	"it87_gp54",
> +	"it87_gp55",
> +	"it87_gp56",
> +	"it87_gp57",
> +	"it87_gp60",
> +	"it87_gp61",
> +	"it87_gp62",
> +	"it87_gp63",
> +	"it87_gp64",
> +	"it87_gp65",
> +	"it87_gp66",
> +	"it87_gp67",
> +	"it87_gp70",
> +	"it87_gp71",
> +	"it87_gp72",
> +	"it87_gp73",
> +	"it87_gp74",
> +	"it87_gp75",
> +	"it87_gp76",
> +	"it87_gp77",
> +	"it87_gp80",
> +	"it87_gp81",
> +	"it87_gp82",
> +	"it87_gp83",
> +	"it87_gp84",
> +	"it87_gp85",
> +	"it87_gp86",
> +	"it87_gp87"
> +};
> +
> +static struct gpio_chip it87_gpio_chip = {
> +	.label			= GPIO_NAME,
> +	.owner			= THIS_MODULE,
> +	.request		= it87_gpio_request,
> +	.get			= it87_gpio_get,
> +	.direction_input	= it87_gpio_direction_in,
> +	.set			= it87_gpio_set,
> +	.direction_output	= it87_gpio_direction_out,
> +	.names			= it87_gpio_aliases
> +};
> +
> +static int __init it87_gpio_init(void)
> +{
> +	int rc = 0;
> +	u8 chip_rev;
> +	u16 chip_type;
> +
> +	if ((rc = superio_enter()))
> +		return rc;
> +
> +	chip_type = superio_inw(CHIPID);
> +	chip_rev  = superio_inb(CHIPREV) & 0x0f;
> +	superio_exit();
> +
> +	switch(chip_type) {
> +	case IT8728_ID:
> +		break;
> +	case NO_DEV_ID:
> +		printk(KERN_ERR PFX "no device\n");
> +		return -ENODEV;
> +	default:
> +		printk(KERN_ERR PFX
> +		       "Unknown Chip found, Chip %04x Revision %x\n",
> +		       chip_type, chip_rev);
> +		return -ENODEV;
> +	}
> +
> +	if ((rc = superio_enter()))
> +		return rc;
> +
> +	superio_select(GPIO);
> +
> +	/* fetch GPIO base address */
> +	gpio_ba = superio_inw(GPIO_BASE);
> +
> +	superio_exit();
> +
> +	if (!request_region(gpio_ba, GPIO_IOSIZE, GPIO_NAME))
> +		return -EBUSY;
> +
> +	it87_gpio_chip.base = -1;
> +	it87_gpio_chip.ngpio = 64;
> +
> +	if ((rc = gpiochip_add(&it87_gpio_chip)) < 0)
> +		goto gpiochip_add_err;
> +
> +	return 0;
> +
> +gpiochip_add_err:
> +	release_region(gpio_ba, GPIO_IOSIZE);
> +	gpio_ba = 0;
> +	return rc;
> +}
> +
> +static void __exit it87_gpio_exit(void)
> +{
> +	if (gpio_ba) {
> +		int ret = gpiochip_remove(&it87_gpio_chip);
> +
> +		WARN(ret, "%s(): gpiochip_remove() failed, ret=%d\n",
> +				__func__, ret);
> +
> +		release_region(gpio_ba, GPIO_IOSIZE);
> +		gpio_ba = 0;
> +	}
> +}
> +module_init(it87_gpio_init);
> +module_exit(it87_gpio_exit);
> +
> +MODULE_AUTHOR("Diego Elio Pettenò <flameeyes@...meeyes.eu>");
> +MODULE_DESCRIPTION("GPIO interface for IT87xx Super I/O chips");
> +MODULE_LICENSE("GPL");
> -- 
> 1.7.8.5
> 
> 
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