drivers: gpio: Add support for GPIOs over Moxtet bus

This adds support for interpreting the input and output bits of one
device on Moxtet bus as GPIOs.
This is needed for example by the SFP cage module of Turris Mox.

Link: https://lore.kernel.org/r/20190812161118.21476-5-marek.behun@nic.cz
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/MAINTAINERS b/MAINTAINERS
index 1869e83f514a44f6a16ab28204c263558ff4c624..a71ab252ad7ecdfa31ccd9f5725e381072a2fae5 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1635,6 +1635,7 @@ F:        Documentation/ABI/testing/sysfs-bus-moxtet-devices
 F:     Documentation/devicetree/bindings/bus/moxtet.txt
 F:     include/linux/moxtet.h
 F:     drivers/bus/moxtet.c
+F:     drivers/gpio/gpio-moxtet.c
 
 ARM/EBSA110 MACHINE SUPPORT
 M:     Russell King <linux@armlinux.org.uk>

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index bb13c266c32968be8bd0864ddd2cf00266d910e7..eef4886a3bc33c8f6e7e9c93fe057388452d2e8e 100644 (file)
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1445,6 +1445,15 @@ config GPIO_XRA1403
        help
          GPIO driver for EXAR XRA1403 16-bit SPI-based GPIO expander.
 
+config GPIO_MOXTET
+       tristate "Turris Mox Moxtet bus GPIO expander"
+       depends on MOXTET
+       help
+         Say yes here if you are building for the Turris Mox router.
+         This is the driver needed for configuring the GPIOs via the Moxtet
+         bus. For example the Mox module with SFP cage needs this driver
+         so that phylink can use corresponding GPIOs.
+
 endmenu
 
 menu "USB GPIO expanders"

diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index a4e91175c70805508d2bfe90c567102264bb59ca..2e10caec23ae2db2664c18cb64272073cd7ef32e 100644 (file)
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -93,6 +93,7 @@ obj-$(CONFIG_GPIO_ML_IOH)             += gpio-ml-ioh.o
 obj-$(CONFIG_GPIO_MLXBF)               += gpio-mlxbf.o
 obj-$(CONFIG_GPIO_MM_LANTIQ)           += gpio-mm-lantiq.o
 obj-$(CONFIG_GPIO_MOCKUP)              += gpio-mockup.o
+obj-$(CONFIG_GPIO_MOXTET)              += gpio-moxtet.o
 obj-$(CONFIG_GPIO_MPC5200)             += gpio-mpc5200.o
 obj-$(CONFIG_GPIO_MPC8XXX)             += gpio-mpc8xxx.o
 obj-$(CONFIG_GPIO_MSIC)                        += gpio-msic.o

diff --git a/drivers/gpio/gpio-moxtet.c b/drivers/gpio/gpio-moxtet.c
new file mode 100644 (file)
index 0000000..3fd7299
--- /dev/null
+++ b/drivers/gpio/gpio-moxtet.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Turris Mox Moxtet GPIO expander
+ *
+ *  Copyright (C) 2018 Marek Behun <marek.behun@nic.cz>
+ */
+
+#include <linux/bitops.h>
+#include <linux/gpio/driver.h>
+#include <linux/moxtet.h>
+#include <linux/module.h>
+
+#define MOXTET_GPIO_NGPIOS     12
+#define MOXTET_GPIO_INPUTS     4
+
+struct moxtet_gpio_desc {
+       u16 in_mask;
+       u16 out_mask;
+};
+
+static const struct moxtet_gpio_desc descs[] = {
+       [TURRIS_MOX_MODULE_SFP] = {
+               .in_mask = GENMASK(2, 0),
+               .out_mask = GENMASK(5, 4),
+       },
+};
+
+struct moxtet_gpio_chip {
+       struct device                   *dev;
+       struct gpio_chip                gpio_chip;
+       const struct moxtet_gpio_desc   *desc;
+};
+
+static int moxtet_gpio_get_value(struct gpio_chip *gc, unsigned int offset)
+{
+       struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+       int ret;
+
+       if (chip->desc->in_mask & BIT(offset)) {
+               ret = moxtet_device_read(chip->dev);
+       } else if (chip->desc->out_mask & BIT(offset)) {
+               ret = moxtet_device_written(chip->dev);
+               if (ret >= 0)
+                       ret <<= MOXTET_GPIO_INPUTS;
+       } else {
+               return -EINVAL;
+       }
+
+       if (ret < 0)
+               return ret;
+
+       return !!(ret & BIT(offset));
+}
+
+static void moxtet_gpio_set_value(struct gpio_chip *gc, unsigned int offset,
+                                 int val)
+{
+       struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+       int state;
+
+       state = moxtet_device_written(chip->dev);
+       if (state < 0)
+               return;
+
+       offset -= MOXTET_GPIO_INPUTS;
+
+       if (val)
+               state |= BIT(offset);
+       else
+               state &= ~BIT(offset);
+
+       moxtet_device_write(chip->dev, state);
+}
+
+static int moxtet_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+       struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+
+       /* All lines are hard wired to be either input or output, not both. */
+       if (chip->desc->in_mask & BIT(offset))
+               return 1;
+       else if (chip->desc->out_mask & BIT(offset))
+               return 0;
+       else
+               return -EINVAL;
+}
+
+static int moxtet_gpio_direction_input(struct gpio_chip *gc,
+                                      unsigned int offset)
+{
+       struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+
+       if (chip->desc->in_mask & BIT(offset))
+               return 0;
+       else if (chip->desc->out_mask & BIT(offset))
+               return -ENOTSUPP;
+       else
+               return -EINVAL;
+}
+
+static int moxtet_gpio_direction_output(struct gpio_chip *gc,
+                                       unsigned int offset, int val)
+{
+       struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+
+       if (chip->desc->out_mask & BIT(offset))
+               moxtet_gpio_set_value(gc, offset, val);
+       else if (chip->desc->in_mask & BIT(offset))
+               return -ENOTSUPP;
+       else
+               return -EINVAL;
+
+       return 0;
+}
+
+static int moxtet_gpio_probe(struct device *dev)
+{
+       struct moxtet_gpio_chip *chip;
+       struct device_node *nc = dev->of_node;
+       int id;
+
+       id = to_moxtet_device(dev)->id;
+
+       if (id >= ARRAY_SIZE(descs)) {
+               dev_err(dev, "%pOF Moxtet device id 0x%x is not supported by gpio-moxtet driver\n",
+                       nc, id);
+               return -ENOTSUPP;
+       }
+
+       chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+       if (!chip)
+               return -ENOMEM;
+
+       chip->dev = dev;
+       chip->gpio_chip.parent = dev;
+       chip->desc = &descs[id];
+
+       dev_set_drvdata(dev, chip);
+
+       chip->gpio_chip.label = dev_name(dev);
+       chip->gpio_chip.get_direction = moxtet_gpio_get_direction;
+       chip->gpio_chip.direction_input = moxtet_gpio_direction_input;
+       chip->gpio_chip.direction_output = moxtet_gpio_direction_output;
+       chip->gpio_chip.get = moxtet_gpio_get_value;
+       chip->gpio_chip.set = moxtet_gpio_set_value;
+       chip->gpio_chip.base = -1;
+
+       chip->gpio_chip.ngpio = MOXTET_GPIO_NGPIOS;
+
+       chip->gpio_chip.can_sleep = true;
+       chip->gpio_chip.owner = THIS_MODULE;
+
+       return devm_gpiochip_add_data(dev, &chip->gpio_chip, chip);
+}
+
+static const struct of_device_id moxtet_gpio_dt_ids[] = {
+       { .compatible = "cznic,moxtet-gpio", },
+       {},
+};
+MODULE_DEVICE_TABLE(of, moxtet_gpio_dt_ids);
+
+static const enum turris_mox_module_id moxtet_gpio_module_table[] = {
+       TURRIS_MOX_MODULE_SFP,
+       0,
+};
+
+static struct moxtet_driver moxtet_gpio_driver = {
+       .driver = {
+               .name           = "moxtet-gpio",
+               .of_match_table = moxtet_gpio_dt_ids,
+               .probe          = moxtet_gpio_probe,
+       },
+       .id_table = moxtet_gpio_module_table,
+};
+module_moxtet_driver(moxtet_gpio_driver);
+
+MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");
+MODULE_DESCRIPTION("Turris Mox Moxtet GPIO expander");
+MODULE_LICENSE("GPL v2");