Hi,
The following contains a GPIO based bit bang driver in the same vein as
drivers/i2c/busses/i2c-ixp{4xx,2000}.c.
As the commentary in the patch says, there is a hardware i2c controller
on the PXA2xx so I don't know if this patch would see widespread use.
Since the platform I use it on is not intended for merging you might
reasonably choose not to merge but I thought I'd at least put it out so
it would be available. If you do want to merge it I'll be happy to let
you though ;-)
Signed-off-by: Ian Campbell <icampbell at arcom.com>
Index: 2.6/drivers/i2c/busses/Kconfig
===================================================================
--- 2.6.orig/drivers/i2c/busses/Kconfig 2005-07-29 10:30:42.000000000 +0100
+++ 2.6/drivers/i2c/busses/Kconfig 2005-07-29 10:31:21.000000000 +0100
@@ -152,6 +152,17 @@
tristate "Intel PXA2XX I2C Slave comms support"
depends on I2C_PXA
+config I2C_PXA2XX_GPIO
+ tristate "PXA2xx GPIO-Based I2C Interface"
+ depends on I2C && ARCH_PXA
+ select I2C_ALGOBIT
+ help
+ Say Y here if you have an Intel PXA2xx 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-pxa2xx-gpio.
+
config I2C_PIIX4
tristate "Intel PIIX4"
depends on I2C && PCI
Index: 2.6/drivers/i2c/busses/Makefile
===================================================================
--- 2.6.orig/drivers/i2c/busses/Makefile 2005-07-29 10:30:42.000000000 +0100
+++ 2.6/drivers/i2c/busses/Makefile 2005-07-29 10:31:21.000000000 +0100
@@ -29,6 +29,7 @@
obj-$(CONFIG_I2C_PIIX4) += i2c-piix4.o
obj-$(CONFIG_I2C_PROSAVAGE) += i2c-prosavage.o
obj-$(CONFIG_I2C_PXA) += i2c-pxa.o
+obj-$(CONFIG_I2C_PXA2XX_GPIO) += i2c-pxa2xx-gpio.o
obj-$(CONFIG_I2C_RPXLITE) += i2c-rpx.o
obj-$(CONFIG_I2C_S3C2410) += i2c-s3c2410.o
obj-$(CONFIG_I2C_SAVAGE4) += i2c-savage4.o
Index: 2.6/drivers/i2c/busses/i2c-pxa2xx-gpio.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ 2.6/drivers/i2c/busses/i2c-pxa2xx-gpio.c 2005-07-29 10:55:16.000000000 +0100
@@ -0,0 +1,164 @@
+/* The PXA2xx processors have an i2c controller on chip, however it is
+ * not always possible to use this controller or you may require more
+ * than one i2c bus for your platform. It is possible to create
+ * additional i2c busses using two GPIO lines.
+ *
+ * To use this driver you should create a platform device in your
+ * platform code:
+ *
+ * static struct i2c_pxa2xx_gpio_pins i2c_bus_data = {
+ * .name = "i2c",
+ * .sda = XX, .scl = YY,
+ * };
+ * static struct platform_device i2c_bus_device = {
+ * .name = "pxa2xx-gpio-i2c",
+ * .id = 0,
+ * .num_resources = 0,
+ * .dev = {
+ * .platform_data = &i2c_bus_data,
+ * }
+ * };
+ * [...]
+ * static void __init platform_init(void)
+ * {
+ * [...]
+ * platform_device_register(&i2c_bus_device);
+ * [...]
+ * }
+ *
+ * Copyright (c) 2005 Arcom Control Systems
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/i2c-algo-bit.h>
+
+#include <asm/arch/pxa-regs.h>
+#include <asm/arch/i2c-gpio.h>
+
+#include <asm/hardware.h>
+
+static void pxa2xx_gpio_setscl(void *data, int state)
+{
+ struct i2c_pxa2xx_gpio_pins *pins = data;
+ if (state)
+ GPSR(pins->scl) = GPIO_bit(pins->scl);
+ else
+ GPCR(pins->scl) = GPIO_bit(pins->scl);
+}
+
+static void pxa2xx_gpio_setsda(void *data, int state)
+{
+ struct i2c_pxa2xx_gpio_pins *pins = data;
+ if (state)
+ pxa_gpio_mode(pins->sda | GPIO_IN | GPIO_DFLT_LOW);
+ else
+ pxa_gpio_mode(pins->sda | GPIO_OUT | GPIO_DFLT_LOW);
+}
+
+static int pxa2xx_gpio_getscl(void *data)
+{
+ struct i2c_pxa2xx_gpio_pins *pins = data;
+ return GPLR(pins->scl) & GPIO_bit(pins->scl);
+}
+
+static int pxa2xx_gpio_getsda(void *data)
+{
+ struct i2c_pxa2xx_gpio_pins *pins = data;
+ pxa_gpio_mode(pins->sda | GPIO_IN);
+ return GPLR(pins->sda) & GPIO_bit(pins->sda);
+}
+
+struct pxa2xx_gpio_i2c_drvdata {
+ struct i2c_adapter adapter;
+ struct i2c_algo_bit_data algo_data;
+};
+
+static int pxa2xx_gpio_i2c_probe(struct device *dev)
+{
+ int err;
+ struct platform_device *plat_dev = to_platform_device(dev);
+ struct pxa2xx_gpio_i2c_drvdata *drv_data =
+ kmalloc(sizeof(struct pxa2xx_gpio_i2c_drvdata), GFP_KERNEL);
+ struct i2c_pxa2xx_gpio_pins *pins = dev->platform_data;
+
+ if (!drv_data)
+ return -ENOMEM;
+
+ memzero(drv_data, sizeof(*drv_data));
+
+ drv_data->algo_data.data = pins;
+ drv_data->algo_data.setsda = pxa2xx_gpio_setsda;
+ drv_data->algo_data.setscl = pxa2xx_gpio_setscl;
+ drv_data->algo_data.getsda = pxa2xx_gpio_getsda;
+ drv_data->algo_data.getscl = pxa2xx_gpio_getscl;
+ drv_data->algo_data.udelay = 10;
+ drv_data->algo_data.mdelay = 10;
+ drv_data->algo_data.timeout = 100;
+
+ drv_data->adapter.id = 0xf000; /* fixme */
+ drv_data->adapter.algo_data = &drv_data->algo_data;
+
+ strcpy(drv_data->adapter.name, pins->name);
+
+ drv_data->adapter.dev.parent = &plat_dev->dev;
+
+ pxa_gpio_mode(pins->sda | GPIO_OUT | GPIO_DFLT_HIGH);
+ pxa_gpio_mode(pins->scl | GPIO_OUT | GPIO_DFLT_HIGH);
+
+ 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 int pxa2xx_gpio_i2c_remove(struct device *dev)
+{
+ struct platform_device *plat_dev = to_platform_device(dev);
+ struct pxa2xx_gpio_i2c_drvdata *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 struct device_driver pxa2xx_gpio_i2c_driver = {
+ .name = "pxa2xx-gpio-i2c",
+ .bus = &platform_bus_type,
+ .probe = pxa2xx_gpio_i2c_probe,
+ .remove = pxa2xx_gpio_i2c_remove,
+};
+
+static int __init pxa2xx_gpio_i2c_init(void)
+{
+ return driver_register(&pxa2xx_gpio_i2c_driver);
+}
+
+static void __exit pxa2xx_gpio_i2c_exit(void)
+{
+ driver_unregister(&pxa2xx_gpio_i2c_driver);
+}
+
+module_init(pxa2xx_gpio_i2c_init);
+module_exit(pxa2xx_gpio_i2c_exit);
+
+MODULE_AUTHOR("Ian Campbell <icampbell at arcom.com>");
+MODULE_DESCRIPTION("i2c bus adapter routines for pxa2xx gpio lines");
+MODULE_LICENSE("GPL");
Index: 2.6/include/asm-arm/arch-pxa/i2c-gpio.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ 2.6/include/asm-arm/arch-pxa/i2c-gpio.h 2005-07-29 10:32:13.000000000 +0100
@@ -0,0 +1,10 @@
+#ifndef _INCLUDE_ASM_ARCH_I2C_GPIO_H_
+#define _INCLUDE_ASM_ARCH_I2C_GPIO_H_
+
+struct i2c_pxa2xx_gpio_pins {
+ const char *name;
+ unsigned sda;
+ unsigned scl;
+};
+
+#endif
--
Ian Campbell, Senior Design Engineer
Web: http://www.arcom.com
Arcom, Clifton Road, Direct: +44 (0)1223 403 465
Cambridge CB1 7EA, United Kingdom Phone: +44 (0)1223 411 200
