Re: [PATCH] i2c driver fixes for 2.6.4

Greg KH
2004-03-16T00:02:12Z

ChangeSet 1.1557.61.6, 2004/02/17 15:00:40-08:00, dsaxena@plexity.net

[PATCH] I2C: Support for IXP42x GPIO-based I2C

Following is an updated patch to add support for using the GPIO lines
on an Intel IXP42x SOC for I2C. Changes since last patch include:

- Cleanups as per Jean Delvare's comments

- Rename functions as 42x instead of 425

- Change the comments at the top of the file to better reflect the
purpose of this driver.

This code has been tested with the eeprom client driver and worked
w/o any problems.

drivers/i2c/busses/Kconfig | 11 ++
drivers/i2c/busses/Makefile | 1
drivers/i2c/busses/i2c-ixp42x.c | 180 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 192 insertions(+)

diff -Nru a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
--- a/drivers/i2c/busses/Kconfig Mon Mar 15 14:37:32 2004
+++ b/drivers/i2c/busses/Kconfig Mon Mar 15 14:37:32 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 Mon Mar 15 14:37:32 2004
+++ b/drivers/i2c/busses/Makefile Mon Mar 15 14:37:32 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 Mon Mar 15 14:37:32 2004
@@ -0,0 +1,180 @@
+/*
+ * drivers/i2c/i2c-adap-ixp42x.c
+ *
+ * Intel's IXP42x XScale NPU chipsets (IXP420, 421, 422, 425) do not have
+ * an on board I2C controller but provide 16 GPIO pins that are often
+ * used to create an I2C bus. This driver provides an i2c_adapter
+ * interface that plugs in under algo_bit and drives the GPIO pins
+ * as instructed by the alogorithm driver.
+ *
+ * Author: Deepak Saxena <dsaxena@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: Since different platforms will use different GPIO pins for
+ * I2C, this driver uses an IXP42x-specific platform_data
+ * pointer to pass the GPIO numbers to the driver. This
+ * allows us to support all the different IXP42x platforms
+ * w/o having to put #ifdefs in this driver.
+ *
+ * See arch/arm/mach-ixp42x/ixdp425.c for an example of building a
+ * device list and filling in the ixp42x_i2c_pins data structure
+ * that is passed as the platform_data to this driver.
+ */
+
+#include <linux/config.h>
+#ifdef CONFIG_I2C_DEBUG_BUS
+#define DEBUG 1
+#endif
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+
+#include <asm/hardware.h> /* Pick up IXP42x-specific bits */
+
+static inline int ixp42x_scl_pin(void *data)
+{
+ return ((struct ixp42x_i2c_pins*)data)->scl_pin;
+}
+
+static inline int ixp42x_sda_pin(void *data)
+{
+ return ((struct ixp42x_i2c_pins*)data)->sda_pin;
+}
+
+static void ixp42x_bit_setscl(void *data, int val)
+{
+ gpio_line_set(ixp42x_scl_pin(data), 0);
+ gpio_line_config(ixp42x_scl_pin(data),
+ val ? IXP425_GPIO_IN : IXP425_GPIO_OUT );
+}
+
+static void ixp42x_bit_setsda(void *data, int val)
+{
+ gpio_line_set(ixp42x_sda_pin(data), 0);
+ gpio_line_config(ixp42x_sda_pin(data),
+ val ? IXP425_GPIO_IN : IXP425_GPIO_OUT );
+}
+
+static int ixp42x_bit_getscl(void *data)
+{
+ int scl;
+
+ gpio_line_config(ixp42x_scl_pin(data), IXP425_GPIO_IN );
+ gpio_line_get(ixp42x_scl_pin(data), &scl);
+
+ return scl;
+}
+
+static int ixp42x_bit_getsda(void *data)
+{
+ int sda;
+
+ gpio_line_config(ixp42x_sda_pin(data), IXP425_GPIO_IN );
+ gpio_line_get(ixp42x_sda_pin(data), &sda);
+
+ return sda;
+}
+
+struct ixp42x_i2c_data {
+ struct ixp42x_i2c_pins *gpio_pins;
+ struct i2c_adapter adapter;
+ struct i2c_algo_bit_data algo_data;
+};
+
+static int ixp42x_i2c_remove(struct device *dev)
+{
+ struct platform_device *plat_dev = to_platform_device(dev);
+ struct ixp42x_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 ixp42x_i2c_probe(struct device *dev)
+{
+ int err;
+ struct platform_device *plat_dev = to_platform_device(dev);
+ struct ixp42x_i2c_pins *gpio = plat_dev->dev.platform_data;
+ struct ixp42x_i2c_data *drv_data =
+ kmalloc(sizeof(struct ixp42x_i2c_data), GFP_KERNEL);
+
+ if(!drv_data)
+ return -ENOMEM;
+
+ memzero(drv_data, sizeof(struct ixp42x_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 = ixp42x_bit_setsda;
+ drv_data->algo_data.setscl = ixp42x_bit_setscl;
+ drv_data->algo_data.getsda = ixp42x_bit_getsda;
+ drv_data->algo_data.getscl = ixp42x_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 ixp42x_i2c_driver = {
+ .name = "IXP42X-I2C",
+ .bus = &platform_bus_type,
+ .probe = ixp42x_i2c_probe,
+ .remove = ixp42x_i2c_remove,
+};
+
+static int __init ixp42x_i2c_init(void)
+{
+ return driver_register(&ixp42x_i2c_driver);
+}
+
+static void __exit ixp42x_i2c_exit(void)
+{
+ driver_unregister(&ixp42x_i2c_driver);
+}
+
+module_init(ixp42x_i2c_init);
+module_exit(ixp42x_i2c_exit);
+
+MODULE_DESCRIPTION("GPIO-based I2C driver for IXP42x systems");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
+