i2c: iop: Use GPIO descriptors

The IOP3xx has some elaborate code to directly slam the
GPIO lines multiplexed with I2C down low before enablement,
apparently a workaround for a hardware bug found in the
early chips.

After consulting the developer documentation for IOP80321
and IOP80331 I can clearly see that this may be useful for
IOP80321 family (mach-iop32x) but it is highly dubious for
any 80331 series or later chip: in these chips the lines
are not multiplexed for UARTs.

We convert the code to pass optional GPIO descriptors
and register these only on the 80321-based boards where
it makes sense, optionally obtain them in the driver and
use the gpiod_set_raw_value() to ascertain the line gets
driven low when needed.

The GPIO driver does not give the GPIO chip a reasonable
label so the patch also adds that so that these machine
descriptor tables can be used.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

7 files changed, 40 insertions, 0 deletions

diff --git a/arch/arm/include/asm/hardware/iop3xx.h b/arch/arm/include/asm/hardware/iop3xx.h
index 2594a95ff19a..a15d08160e8f 100644
--- a/arch/arm/include/asm/hardware/iop3xx.h
+++ b/arch/arm/include/asm/hardware/iop3xx.h
@@ -305,6 +305,8 @@ extern struct platform_device iop3xx_dma_1_channel;
 extern struct platform_device iop3xx_aau_channel;
 extern struct platform_device iop3xx_i2c0_device;
 extern struct platform_device iop3xx_i2c1_device;
+extern struct gpiod_lookup_table iop3xx_i2c0_gpio_lookup;
+extern struct gpiod_lookup_table iop3xx_i2c1_gpio_lookup;
 
 #endif
 
diff --git a/arch/arm/mach-iop32x/em7210.c b/arch/arm/mach-iop32x/em7210.c
index 77e1ff057303..d2bcbac6b7f2 100644
--- a/arch/arm/mach-iop32x/em7210.c
+++ b/arch/arm/mach-iop32x/em7210.c
@@ -24,6 +24,7 @@
 #include <linux/platform_device.h>
 #include <linux/i2c.h>
 #include <linux/gpio.h>
+#include <linux/gpio/machine.h>
 #include <mach/hardware.h>
 #include <linux/io.h>
 #include <linux/irq.h>
@@ -211,6 +212,8 @@ static void __init em7210_init_machine(void)
 {
 	register_iop32x_gpio();
 	platform_device_register(&em7210_serial_device);
+	gpiod_add_lookup_table(&iop3xx_i2c0_gpio_lookup);
+	gpiod_add_lookup_table(&iop3xx_i2c1_gpio_lookup);
 	platform_device_register(&iop3xx_i2c0_device);
 	platform_device_register(&iop3xx_i2c1_device);
 	platform_device_register(&em7210_flash_device);
diff --git a/arch/arm/mach-iop32x/glantank.c b/arch/arm/mach-iop32x/glantank.c
index 547b2342d61a..4c4995007d17 100644
--- a/arch/arm/mach-iop32x/glantank.c
+++ b/arch/arm/mach-iop32x/glantank.c
@@ -25,6 +25,7 @@
 #include <linux/i2c.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
+#include <linux/gpio/machine.h>
 #include <mach/hardware.h>
 #include <asm/irq.h>
 #include <asm/mach/arch.h>
@@ -189,6 +190,8 @@ static void glantank_power_off(void)
 static void __init glantank_init_machine(void)
 {
 	register_iop32x_gpio();
+	gpiod_add_lookup_table(&iop3xx_i2c0_gpio_lookup);
+	gpiod_add_lookup_table(&iop3xx_i2c1_gpio_lookup);
 	platform_device_register(&iop3xx_i2c0_device);
 	platform_device_register(&iop3xx_i2c1_device);
 	platform_device_register(&glantank_flash_device);
diff --git a/arch/arm/mach-iop32x/iq31244.c b/arch/arm/mach-iop32x/iq31244.c
index 0e1392b20d18..56a64ffd3824 100644
--- a/arch/arm/mach-iop32x/iq31244.c
+++ b/arch/arm/mach-iop32x/iq31244.c
@@ -26,6 +26,7 @@
 #include <linux/mtd/physmap.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
+#include <linux/gpio/machine.h>
 #include <mach/hardware.h>
 #include <asm/cputype.h>
 #include <asm/irq.h>
@@ -285,6 +286,8 @@ void ep80219_power_off(void)
 static void __init iq31244_init_machine(void)
 {
 	register_iop32x_gpio();
+	gpiod_add_lookup_table(&iop3xx_i2c0_gpio_lookup);
+	gpiod_add_lookup_table(&iop3xx_i2c1_gpio_lookup);
 	platform_device_register(&iop3xx_i2c0_device);
 	platform_device_register(&iop3xx_i2c1_device);
 	platform_device_register(&iq31244_flash_device);
diff --git a/arch/arm/mach-iop32x/iq80321.c b/arch/arm/mach-iop32x/iq80321.c
index 66782ff1f46a..02abbf9efd54 100644
--- a/arch/arm/mach-iop32x/iq80321.c
+++ b/arch/arm/mach-iop32x/iq80321.c
@@ -23,6 +23,7 @@
 #include <linux/mtd/physmap.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
+#include <linux/gpio/machine.h>
 #include <mach/hardware.h>
 #include <asm/irq.h>
 #include <asm/mach/arch.h>
@@ -172,6 +173,8 @@ static struct platform_device iq80321_serial_device = {
 static void __init iq80321_init_machine(void)
 {
 	register_iop32x_gpio();
+	gpiod_add_lookup_table(&iop3xx_i2c0_gpio_lookup);
+	gpiod_add_lookup_table(&iop3xx_i2c1_gpio_lookup);
 	platform_device_register(&iop3xx_i2c0_device);
 	platform_device_register(&iop3xx_i2c1_device);
 	platform_device_register(&iq80321_flash_device);
diff --git a/arch/arm/mach-iop32x/n2100.c b/arch/arm/mach-iop32x/n2100.c
index 23e8c93515d4..c780b6e82ad9 100644
--- a/arch/arm/mach-iop32x/n2100.c
+++ b/arch/arm/mach-iop32x/n2100.c
@@ -31,6 +31,7 @@
 #include <linux/reboot.h>
 #include <linux/io.h>
 #include <linux/gpio.h>
+#include <linux/gpio/machine.h>
 #include <mach/hardware.h>
 #include <asm/irq.h>
 #include <asm/mach/arch.h>
@@ -345,6 +346,7 @@ device_initcall(n2100_request_gpios);
 static void __init n2100_init_machine(void)
 {
 	register_iop32x_gpio();
+	gpiod_add_lookup_table(&iop3xx_i2c0_gpio_lookup);
 	platform_device_register(&iop3xx_i2c0_device);
 	platform_device_register(&n2100_flash_device);
 	platform_device_register(&n2100_serial_device);
diff --git a/arch/arm/plat-iop/i2c.c b/arch/arm/plat-iop/i2c.c
index 88215ad031a2..bac20f7f5f8a 100644
--- a/arch/arm/plat-iop/i2c.c
+++ b/arch/arm/plat-iop/i2c.c
@@ -19,6 +19,7 @@
 #include <linux/tty.h>
 #include <linux/serial_core.h>
 #include <linux/io.h>
+#include <linux/gpio/machine.h>
 #include <asm/pgtable.h>
 #include <asm/page.h>
 #include <asm/mach/map.h>
@@ -37,6 +38,29 @@
 #define IRQ_IOP3XX_I2C_1	IRQ_IOP33X_I2C_1
 #endif
 
+/*
+ * Each of the I2C busses have corresponding GPIO lines, and the driver
+ * need to access these directly to drive the bus low at times.
+ */
+
+struct gpiod_lookup_table iop3xx_i2c0_gpio_lookup = {
+	.dev_id = "IOP3xx-I2C.0",
+	.table = {
+		GPIO_LOOKUP("gpio-iop", 7, "scl", GPIO_ACTIVE_HIGH),
+		GPIO_LOOKUP("gpio-iop", 6, "sda", GPIO_ACTIVE_HIGH),
+		{ }
+	},
+};
+
+struct gpiod_lookup_table iop3xx_i2c1_gpio_lookup = {
+	.dev_id = "IOP3xx-I2C.1",
+	.table = {
+		GPIO_LOOKUP("gpio-iop", 5, "scl", GPIO_ACTIVE_HIGH),
+		GPIO_LOOKUP("gpio-iop", 4, "sda", GPIO_ACTIVE_HIGH),
+		{ }
+	},
+};
+
 static struct resource iop3xx_i2c0_resources[] = {
 	[0] = {
 		.start	= 0xfffff680,