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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>
alistair/sunxi64-5.4-dsi
Marek Behún 2019-08-12 18:11:17 +02:00 committed by Arnd Bergmann
parent 2091b417aa
commit 856ed97af5
4 changed files with 190 additions and 0 deletions
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1
MAINTAINERS
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@ -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>

9
drivers/gpio/Kconfig
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@ -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"

1
drivers/gpio/Makefile
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@ -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

179
drivers/gpio/gpio-moxtet.c 100644
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@ -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");