ar71xx: Add kernel 4.9 support

This add support for kernel 4.9 to the ar71xx target.
It was compile tested with the generic, NAND and mikrotik subtarget.
Multiple members of the community tested it on their boards and did not
report any major problem so far.

Especially the NAND part received some changes to adapt to the new
kernel APIs. The serial driver hack used for the Arduino Yun was not
ported because the kernel changed there a lot.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

1 files changed, 117 insertions, 0 deletions

diff --git a/target/linux/ar71xx/patches-4.9/451-gpio-74x164-improve-platform-device-support.patch b/target/linux/ar71xx/patches-4.9/451-gpio-74x164-improve-platform-device-support.patch
new file mode 100644
index 0000000000..d9cfa888fb
--- /dev/null
+++ b/target/linux/ar71xx/patches-4.9/451-gpio-74x164-improve-platform-device-support.patch
@@ -0,0 +1,117 @@
+--- a/drivers/gpio/gpio-74x164.c
++++ b/drivers/gpio/gpio-74x164.c
+@@ -12,6 +12,7 @@
+ #include <linux/init.h>
+ #include <linux/mutex.h>
+ #include <linux/spi/spi.h>
++#include <linux/spi/74x164.h>
+ #include <linux/gpio.h>
+ #include <linux/of_gpio.h>
+ #include <linux/slab.h>
+@@ -103,9 +104,16 @@ static int gen_74x164_direction_output(s
+ static int gen_74x164_probe(struct spi_device *spi)
+ {
+ 	struct gen_74x164_chip *chip;
++	struct gen_74x164_chip_platform_data *pdata = spi->dev.platform_data;
++	struct device_node *np = spi->dev.of_node;
+ 	u32 nregs;
+ 	int ret;
+ 
++	if (!np && !pdata) {
++		dev_err(&spi->dev, "No configuration data available.\n");
++		return -EINVAL;
++	}
++
+ 	/*
+ 	 * bits_per_word cannot be configured in platform data
+ 	 */
+@@ -115,17 +123,23 @@ static int gen_74x164_probe(struct spi_d
+ 	if (ret < 0)
+ 		return ret;
+ 
+-	if (of_property_read_u32(spi->dev.of_node, "registers-number",
+-				 &nregs)) {
+-		dev_err(&spi->dev,
+-			"Missing registers-number property in the DT.\n");
+-		return -EINVAL;
+-	}
++	if (np) {
++		if (of_property_read_u32(np, "registers-number", &nregs)) {
++			dev_err(&spi->dev,
++				"Missing registers-number property in the DT.\n");
++			return -EINVAL;
++		}
++	} else if (pdata) {
++		nregs = pdata->num_registers;
++ 	}
+ 
+ 	chip = devm_kzalloc(&spi->dev, sizeof(*chip) + nregs, GFP_KERNEL);
+ 	if (!chip)
+ 		return -ENOMEM;
+ 
++	if (pdata && pdata->init_data)
++		memcpy(chip->buffer, pdata->init_data, chip->registers);
++	
+ 	spi_set_drvdata(spi, chip);
+ 
+ 	chip->gpio_chip.label = spi->modalias;
+@@ -133,7 +147,11 @@ static int gen_74x164_probe(struct spi_d
+ 	chip->gpio_chip.get = gen_74x164_get_value;
+ 	chip->gpio_chip.set = gen_74x164_set_value;
+ 	chip->gpio_chip.set_multiple = gen_74x164_set_multiple;
+-	chip->gpio_chip.base = -1;
++	if (np)
++		chip->gpio_chip.base = -1;
++	else if (pdata)
++		chip->gpio_chip.base = pdata->base;
++
+ 
+ 	chip->registers = nregs;
+ 	chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers;
+@@ -170,17 +188,19 @@ static int gen_74x164_remove(struct spi_
+ 	return 0;
+ }
+ 
++#ifdef CONFIG_OF
+ static const struct of_device_id gen_74x164_dt_ids[] = {
+ 	{ .compatible = "fairchild,74hc595" },
+ 	{ .compatible = "nxp,74lvc594" },
+ 	{},
+ };
+ MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids);
++#endif
+ 
+ static struct spi_driver gen_74x164_driver = {
+ 	.driver = {
+ 		.name		= "74x164",
+-		.of_match_table	= gen_74x164_dt_ids,
++		.of_match_table	= of_match_ptr(gen_74x164_dt_ids),
+ 	},
+ 	.probe		= gen_74x164_probe,
+ 	.remove		= gen_74x164_remove,
+--- /dev/null
++++ b/include/linux/spi/74x164.h
+@@ -0,0 +1,13 @@
++#ifndef LINUX_SPI_74X164_H
++#define LINUX_SPI_74X164_H
++
++struct gen_74x164_chip_platform_data {
++	/* number assigned to the first GPIO */
++	unsigned        base;
++	/* number of chained registers */
++	unsigned	num_registers;
++	/* address of a buffer containing initial data */
++	u8		*init_data;
++};
++
++#endif
+--- a/drivers/gpio/Kconfig
++++ b/drivers/gpio/Kconfig
+@@ -1154,7 +1154,6 @@ menu "SPI GPIO expanders"
+ 
+ config GPIO_74X164
+ 	tristate "74x164 serial-in/parallel-out 8-bits shift register"
+-	depends on OF_GPIO
+ 	help
+ 	  Driver for 74x164 compatible serial-in/parallel-out 8-outputs
+ 	  shift registers. This driver can be used to provide access