This is quite board-specific.
By definition General Purpose I/O are General Purpose.
Why should the kernel have a GPIO-based I2C driver?
Is separating the GPIO definitions into your_platform.c (please provide example...)
really provide much benefit compared to just writing a driver
for each motherboard?
Deepak Saxena wrote:
> Greg,
>
> The following patch against Linus' BK tree adds a driver for using GPIO
> pins on Intel's IXP42x ARM SOCs for an I2C interface.
>
> Tnx,
> ~Deepak
>
> diff -Nru a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> --- a/drivers/i2c/busses/Kconfig Fri Feb 13 16:56:09 2004
> +++ b/drivers/i2c/busses/Kconfig Fri Feb 13 16:56:09 2004
> @@ -144,6 +144,17 @@
> This support is also available as a module. If so, the module
> will be called i2c-ite.
>
> +config I2C_IXP42X
> + tristate "IXP42x GPIO-Based I2C Interface"
> + depends on I2C && ARCH_IXP425
> + select I2C_ALGOBIT
> + help
> + Say Y here if you have an Intel IXP42x(420,421,422,425) based
> + system and are using GPIO lines for an I2C bus.
> +
> + This support is also available as a module. If so, the module
> + will be called i2c-ixp42x.
> +
> config I2C_KEYWEST
> tristate "Powermac Keywest I2C interface"
> depends on I2C && PPC_PMAC
> diff -Nru a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> --- a/drivers/i2c/busses/Makefile Fri Feb 13 16:56:09 2004
> +++ b/drivers/i2c/busses/Makefile Fri Feb 13 16:56:09 2004
> @@ -15,6 +15,7 @@
> obj-$(CONFIG_I2C_IOP3XX) += i2c-iop3xx.o
> obj-$(CONFIG_I2C_ISA) += i2c-isa.o
> obj-$(CONFIG_I2C_ITE) += i2c-ite.o
> +obj-$(CONFIG_I2C_IXP42X) += i2c-ixp42x.o
> obj-$(CONFIG_I2C_KEYWEST) += i2c-keywest.o
> obj-$(CONFIG_I2C_NFORCE2) += i2c-nforce2.o
> obj-$(CONFIG_I2C_PHILIPSPAR) += i2c-philips-par.o
> diff -Nru a/drivers/i2c/busses/i2c-ixp42x.c b/drivers/i2c/busses/i2c-ixp42x.c
> --- /dev/null Wed Dec 31 16:00:00 1969
> +++ b/drivers/i2c/busses/i2c-ixp42x.c Fri Feb 13 16:56:09 2004
> @@ -0,0 +1,170 @@
> +/*
> + * drivers/i2c/i2c-adap-ixp425.c
> + *
> + * Driver for gpio-based i2c adapter on Intel IXP42x systems.
> + *
> + * Author: Deepak Saxena <dsaxena at plexity.net>
> + *
> + * Copyright (c) 2003-2004 MontaVista Software Inc.
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + *
> + * NOTE: Do NOT add board specific hooks here. All that belongs in platform
> + * specific code in arch/arm/mach-ixp425/your_platform.c. See
> + * arch/arm/mach-ixp425/ixdp425.c for an example of building a
> + * device list and filling in the ixp425_i2c_pins data structure
> + * that is passed as the platform_data to this driver.
> + */
> +
> +#include <linux/config.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/i2c-algo-bit.h>
> +#include <linux/i2c-id.h>
> +
> +#include <asm/hardware.h>
> +
> +static inline int ixp425_scl_pin(void *data)
> +{
> + return ((struct ixp425_i2c_pins*)data)->scl_pin;
> +}
> +
> +static inline int ixp425_sda_pin(void *data)
> +{
> + return ((struct ixp425_i2c_pins*)data)->sda_pin;
> +}
> +
> +static void ixdp425_bit_setscl(void *data, int val)
> +{
> + gpio_line_set(ixp425_scl_pin(data), 0);
> + gpio_line_config(ixp425_scl_pin(data),
> + val ? IXP425_GPIO_IN : IXP425_GPIO_OUT );
> +}
> +
> +static void ixdp425_bit_setsda(void *data, int val)
> +{
> + gpio_line_set(ixp425_sda_pin(data), 0);
> + gpio_line_config(ixp425_sda_pin(data),
> + val ? IXP425_GPIO_IN : IXP425_GPIO_OUT );
> +}
> +
> +static int ixdp425_bit_getscl(void *data)
> +{
> + int scl;
> +
> + gpio_line_config(ixp425_scl_pin(data), IXP425_GPIO_IN );
> + gpio_line_get(ixp425_scl_pin(data), &scl);
> +
> + return scl;
> +}
> +
> +static int ixdp425_bit_getsda(void *data)
> +{
> + int sda;
> +
> + gpio_line_config(ixp425_sda_pin(data), IXP425_GPIO_IN );
> + gpio_line_get(ixp425_sda_pin(data), &sda);
> +
> + return sda;
> +}
> +
> +struct ixp425_i2c_data {
> + struct ixp425_i2c_pins *gpio_pins;
> + struct i2c_adapter adapter;
> + struct i2c_algo_bit_data algo_data;
> +};
> +
> +static int ixp425_i2c_remove(struct device *dev)
> +{
> + struct platform_device *plat_dev = to_platform_device(dev);
> + struct ixp425_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);
> +
> + dev_set_drvdata(&plat_dev->dev, NULL);
> +
> + i2c_bit_del_bus(&drv_data->adapter);
> +
> + kfree(drv_data);
> +
> + return 0;
> +}
> +
> +static int ixp425_i2c_probe(struct device *dev)
> +{
> + int err;
> + struct platform_device *plat_dev = to_platform_device(dev);
> + struct ixp425_i2c_pins *gpio = plat_dev->dev.platform_data;
> + struct ixp425_i2c_data *drv_data =
> + kmalloc(sizeof(struct ixp425_i2c_data), GFP_KERNEL);
> +
> + if(!drv_data)
> + return -ENOMEM;
> +
> + memzero(drv_data, sizeof(struct ixp425_i2c_data));
> + drv_data->gpio_pins = gpio;
> +
> + /*
> + * We could make a lot of these structures static, but
> + * certain platforms may have multiple GPIO-based I2C
> + * buses for various device domains, so we need per-device
> + * algo_data->data.
> + */
> + drv_data->algo_data.data = gpio;
> + drv_data->algo_data.setsda = ixdp425_bit_setsda;
> + drv_data->algo_data.setscl = ixdp425_bit_setscl;
> + drv_data->algo_data.getsda = ixdp425_bit_getsda;
> + drv_data->algo_data.getscl = ixdp425_bit_getscl;
> + drv_data->algo_data.udelay = 10;
> + drv_data->algo_data.mdelay = 10;
> + drv_data->algo_data.timeout = 100;
> +
> + drv_data->adapter.id = I2C_HW_B_IXP425,
> + drv_data->adapter.algo_data = &drv_data->algo_data,
> +
> + drv_data->adapter.dev.parent = &plat_dev->dev;
> +
> + gpio_line_config(gpio->scl_pin, IXP425_GPIO_IN);
> + gpio_line_config(gpio->sda_pin, IXP425_GPIO_IN);
> + gpio_line_set(gpio->scl_pin, 0);
> + gpio_line_set(gpio->sda_pin, 0);
> +
> + if ((err = i2c_bit_add_bus(&drv_data->adapter) != 0)) {
> + printk(KERN_ERR "ERROR: Could not install %s\n", dev->bus_id);
> +
> + kfree(drv_data);
> + return err;
> + }
> +
> + dev_set_drvdata(&plat_dev->dev, drv_data);
> +
> + return 0;
> +}
> +
> +static struct device_driver ixp425_i2c_driver = {
> + .name = "IXP425-I2C",
> + .bus = &platform_bus_type,
> + .probe = ixp425_i2c_probe,
> + .remove = ixp425_i2c_remove,
> +};
> +
> +static int __init ixp425_i2c_init(void)
> +{
> + return driver_register(&ixp425_i2c_driver);
> +}
> +
> +static void __exit ixp425_i2c_exit(void)
> +{
> + driver_unregister(&ixp425_i2c_driver);
> +}
> +
> +module_init(ixp425_i2c_init);
> +module_exit(ixp425_i2c_exit);
> +
> +MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP425 systems");
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Deepak Saxena<dsaxena at plexity.net>");
> +
>
