[ARM] 4650/1: AT91: New-style init of I2C, support for i2c-gpio
The AT91 I2C driver is currently marked as "broken" due to hardware
issues. This patch enables AT91-based platforms to also use the
bitbanged GPIO for I2C.
This updates platform setup logic (setting up an i2c-gpio device
using the same pins as the i2c-at91 device, unless only the BROKEN
driver is enabled).
Also make use of the new-style initialization of I2C devices using
i2c_register_board_info().
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-at91/at91sam9rl_devices.c b/arch/arm/mach-at91/at91sam9rl_devices.c
index cd7532b..2bd60a3 100644
--- a/arch/arm/mach-at91/at91sam9rl_devices.c
+++ b/arch/arm/mach-at91/at91sam9rl_devices.c
@@ -10,8 +10,9 @@
#include <asm/mach/map.h>
#include <linux/platform_device.h>
-#include <linux/fb.h>
+#include <linux/i2c-gpio.h>
+#include <linux/fb.h>
#include <video/atmel_lcdc.h>
#include <asm/arch/board.h>
@@ -169,7 +170,40 @@
* TWI (i2c)
* -------------------------------------------------------------------- */
-#if defined(CONFIG_I2C_AT91) || defined(CONFIG_I2C_AT91_MODULE)
+/*
+ * Prefer the GPIO code since the TWI controller isn't robust
+ * (gets overruns and underruns under load) and can only issue
+ * repeated STARTs in one scenario (the driver doesn't yet handle them).
+ */
+#if defined(CONFIG_I2C_GPIO) || defined(CONFIG_I2C_GPIO_MODULE)
+
+static struct i2c_gpio_platform_data pdata = {
+ .sda_pin = AT91_PIN_PA23,
+ .sda_is_open_drain = 1,
+ .scl_pin = AT91_PIN_PA24,
+ .scl_is_open_drain = 1,
+ .udelay = 2, /* ~100 kHz */
+};
+
+static struct platform_device at91sam9rl_twi_device = {
+ .name = "i2c-gpio",
+ .id = -1,
+ .dev.platform_data = &pdata,
+};
+
+void __init at91_add_device_i2c(struct i2c_board_info *devices, int nr_devices)
+{
+ at91_set_GPIO_periph(AT91_PIN_PA23, 1); /* TWD (SDA) */
+ at91_set_multi_drive(AT91_PIN_PA23, 1);
+
+ at91_set_GPIO_periph(AT91_PIN_PA24, 1); /* TWCK (SCL) */
+ at91_set_multi_drive(AT91_PIN_PA24, 1);
+
+ i2c_register_board_info(0, devices, nr_devices);
+ platform_device_register(&at91sam9rl_twi_device);
+}
+
+#elif defined(CONFIG_I2C_AT91) || defined(CONFIG_I2C_AT91_MODULE)
static struct resource twi_resources[] = {
[0] = {
@@ -191,7 +225,7 @@
.num_resources = ARRAY_SIZE(twi_resources),
};
-void __init at91_add_device_i2c(void)
+void __init at91_add_device_i2c(struct i2c_board_info *devices, int nr_devices)
{
/* pins used for TWI interface */
at91_set_A_periph(AT91_PIN_PA23, 0); /* TWD */
@@ -200,10 +234,11 @@
at91_set_A_periph(AT91_PIN_PA24, 0); /* TWCK */
at91_set_multi_drive(AT91_PIN_PA24, 1);
+ i2c_register_board_info(0, devices, nr_devices);
platform_device_register(&at91sam9rl_twi_device);
}
#else
-void __init at91_add_device_i2c(void) {}
+void __init at91_add_device_i2c(struct i2c_board_info *devices, int nr_devices) {}
#endif