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>

1 files changed, 2 insertions, 0 deletions

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);