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SubjectRe: [PATCH 12/18] gpio: add support for the sl28cpld GPIO controller
Hi Bartosz,

Am 2020-03-25 12:50, schrieb Bartosz Golaszewski:
> śr., 18 mar 2020 o 13:45 Michael Walle <michael@walle.cc> napisał(a):
>>
>> Hi Bartosz,
>>
>> Am 2020-03-18 10:14, schrieb Bartosz Golaszewski:
>> > wt., 17 mar 2020 o 21:50 Michael Walle <michael@walle.cc> napisał(a):
>> >>
>> >> This adds support for the GPIO controller of the sl28 board management
>> >> controller. This driver is part of a multi-function device.
>> >>
>> >> Signed-off-by: Michael Walle <michael@walle.cc>
>> >
>> > Hi Michael,
>> >
>> > thanks for the driver. Please take a look at some comments below.
>>
>> well, thank you for the very fast review!
>>
>> >> ---
>> >> drivers/gpio/Kconfig | 11 ++
>> >> drivers/gpio/Makefile | 1 +
>> >> drivers/gpio/gpio-sl28cpld.c | 332
>> >> +++++++++++++++++++++++++++++++++++
>> >> 3 files changed, 344 insertions(+)
>> >> create mode 100644 drivers/gpio/gpio-sl28cpld.c
>> >>
>> >> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
>> >> index 3cbf8882a0dd..516e47017ef5 100644
>> >> --- a/drivers/gpio/Kconfig
>> >> +++ b/drivers/gpio/Kconfig
>> >> @@ -1211,6 +1211,17 @@ config GPIO_RC5T583
>> >> This driver provides the support for driving/reading the
>> >> gpio pins
>> >> of RC5T583 device through standard gpio library.
>> >>
>> >> +config GPIO_SL28CPLD
>> >> + tristate "Kontron sl28 GPIO"
>> >> + depends on MFD_SL28CPLD
>> >> + depends on OF_GPIO
>> >> + select GPIOLIB_IRQCHIP
>> >
>> > Please see below - I think both are not needed.
>> >
>> >> + help
>> >> + This enables support for the GPIOs found on the Kontron sl28
>> >> CPLD.
>> >> +
>> >> + This driver can also be built as a module. If so, the module
>> >> will be
>> >> + called gpio-sl28cpld.
>> >> +
>> >> config GPIO_STMPE
>> >> bool "STMPE GPIOs"
>> >> depends on MFD_STMPE
>> >> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
>> >> index 0b571264ddbc..0ca2d52c78e8 100644
>> >> --- a/drivers/gpio/Makefile
>> >> +++ b/drivers/gpio/Makefile
>> >> @@ -127,6 +127,7 @@ obj-$(CONFIG_GPIO_SCH311X) +=
>> >> gpio-sch311x.o
>> >> obj-$(CONFIG_GPIO_SCH) += gpio-sch.o
>> >> obj-$(CONFIG_GPIO_SIFIVE) += gpio-sifive.o
>> >> obj-$(CONFIG_GPIO_SIOX) += gpio-siox.o
>> >> +obj-$(CONFIG_GPIO_SL28CPLD) += gpio-sl28cpld.o
>> >> obj-$(CONFIG_GPIO_SODAVILLE) += gpio-sodaville.o
>> >> obj-$(CONFIG_GPIO_SPEAR_SPICS) += gpio-spear-spics.o
>> >> obj-$(CONFIG_GPIO_SPRD) += gpio-sprd.o
>> >> diff --git a/drivers/gpio/gpio-sl28cpld.c
>> >> b/drivers/gpio/gpio-sl28cpld.c
>> >> new file mode 100644
>> >> index 000000000000..94f82013882f
>> >> --- /dev/null
>> >> +++ b/drivers/gpio/gpio-sl28cpld.c
>> >> @@ -0,0 +1,332 @@
>> >> +// SPDX-License-Identifier: GPL-2.0-only
>> >> +/*
>> >> + * SMARC-sAL28 GPIO driver.
>> >> + *
>> >> + * Copyright 2019 Kontron Europe GmbH
>> >> + */
>> >> +
>> >> +#include <linux/kernel.h>
>> >> +#include <linux/module.h>
>> >> +#include <linux/of.h>
>> >> +#include <linux/of_device.h>
>> >> +#include <linux/of_address.h>
>> >> +#include <linux/interrupt.h>
>> >> +#include <linux/regmap.h>
>> >> +#include <linux/platform_device.h>
>> >> +#include <linux/gpio/driver.h>
>> >> +
>> >> +#define GPIO_REG_DIR 0
>> >> +#define GPIO_REG_OUT 1
>> >> +#define GPIO_REG_IN 2
>> >> +#define GPIO_REG_IE 3
>> >> +#define GPIO_REG_IP 4
>> >
>> > These values would be more clear if they were defined as hex.
>> >
>> >> +
>> >> +#define GPI_REG_IN 0
>> >> +
>> >> +#define GPO_REG_OUT 0
>> >
>> > Please also use a common prefix even for defines.
>>
>> ok
>>
>> >
>> >> +
>> >> +enum sl28cpld_gpio_type {
>> >> + sl28cpld_gpio,
>> >> + sl28cpld_gpi,
>> >> + sl28cpld_gpo,
>> >> +};
>> >
>> > Enum values should be all upper-case.
>>
>> ok
>>
>> >> +
>> >> +struct sl28cpld_gpio {
>> >> + struct gpio_chip gpio_chip;
>> >> + struct irq_chip irq_chip;
>> >> + struct regmap *regmap;
>> >> + u32 offset;
>> >> + struct mutex lock;
>> >> + u8 ie;
>> >> +};
>> >> +
>> >> +static void sl28cpld_gpio_set_reg(struct gpio_chip *chip, unsigned
>> >> int reg,
>> >> + unsigned int offset, int value)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio = gpiochip_get_data(chip);
>> >> + unsigned int mask = 1 << offset;
>> >> + unsigned int val = value << offset;
>> >> +
>> >> + regmap_update_bits(gpio->regmap, gpio->offset + reg, mask,
>> >> val);
>> >> +}
>> >> +
>> >> +static void sl28cpld_gpio_set(struct gpio_chip *chip, unsigned int
>> >> offset,
>> >> + int value)
>> >> +{
>> >> + sl28cpld_gpio_set_reg(chip, GPIO_REG_OUT, offset, value);
>> >> +}
>> >> +
>> >> +static void sl28cpld_gpo_set(struct gpio_chip *chip, unsigned int
>> >> offset,
>> >> + int value)
>> >> +{
>> >> + sl28cpld_gpio_set_reg(chip, GPO_REG_OUT, offset, value);
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpio_get_reg(struct gpio_chip *chip, unsigned int
>> >> reg,
>> >> + unsigned int offset)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio = gpiochip_get_data(chip);
>> >> + unsigned int mask = 1 << offset;
>> >> + unsigned int val;
>> >> + int ret;
>> >> +
>> >> + ret = regmap_read(gpio->regmap, gpio->offset + reg, &val);
>> >> + if (ret)
>> >> + return ret;
>> >> +
>> >> + return (val & mask) ? 1 : 0;
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpio_get(struct gpio_chip *chip, unsigned int
>> >> offset)
>> >> +{
>> >> + return sl28cpld_gpio_get_reg(chip, GPIO_REG_IN, offset);
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpi_get(struct gpio_chip *chip, unsigned int
>> >> offset)
>> >> +{
>> >> + return sl28cpld_gpio_get_reg(chip, GPI_REG_IN, offset);
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpio_get_direction(struct gpio_chip *chip,
>> >> + unsigned int offset)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio = gpiochip_get_data(chip);
>> >> + unsigned int reg;
>> >> + int ret;
>> >> +
>> >> + ret = regmap_read(gpio->regmap, gpio->offset + GPIO_REG_DIR,
>> >> &reg);
>> >> + if (ret)
>> >> + return ret;
>> >> +
>> >> + if (reg & (1 << offset))
>> >> + return GPIO_LINE_DIRECTION_OUT;
>> >> + else
>> >> + return GPIO_LINE_DIRECTION_IN;
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpio_set_direction(struct gpio_chip *chip,
>> >> + unsigned int offset,
>> >> + bool output)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio = gpiochip_get_data(chip);
>> >> + unsigned int mask = 1 << offset;
>> >> + unsigned int val = (output) ? mask : 0;
>> >> +
>> >> + return regmap_update_bits(gpio->regmap, gpio->offset +
>> >> GPIO_REG_DIR,
>> >> + mask, val);
>> >> +
>> >
>> > Stray newline.
>> ok
>>
>> >
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpio_direction_input(struct gpio_chip *chip,
>> >> + unsigned int offset)
>> >> +{
>> >> + return sl28cpld_gpio_set_direction(chip, offset, false);
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpio_direction_output(struct gpio_chip *chip,
>> >> + unsigned int offset, int
>> >> value)
>> >> +{
>> >> + sl28cpld_gpio_set_reg(chip, GPIO_REG_OUT, offset, value);
>> >> + return sl28cpld_gpio_set_direction(chip, offset, true);
>> >> +}
>> >> +
>> >> +static void sl28cpld_gpio_irq_lock(struct irq_data *data)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio =
>> >> + gpiochip_get_data(irq_data_get_irq_chip_data(data));
>> >> +
>> >> + mutex_lock(&gpio->lock);
>> >
>> > How does that actually lock anything?
>>
>> TBH, I took that from gpio-pcf857x.c. But that
>> (1) don't uses regmap
>> (2) also uses that lock on other places.
>>
>> I'll dig deeper into that and try to understand why there is a lock at
>> all and why this callback is actually called _irq_lock() because that
>> made me wonder.
>>
>> > Regmap uses a different lock and
>> > if you want to make sure nobody modifies the GPIO registers than you'd
>> > need to use the same lock. Also: this looks a lot like a task for
>> > regmap_irqchip - maybe you could use it here or in the core mfd
>> > module?
>>
>> regmap_irqchip will register the interrupt controller on the device
>> which owns the regmap, ie. the parent. So (1) the phandle would need
>> to
>> point to the parent device instead of the GPIO subnode and (2) I'm
>> already using the regmap_irqchip for the interrupt controller. I don't
>> know if you can actually have that multiple times.
>>
>> there was a discussion which might apply partly to (1):
>> https://lore.kernel.org/patchwork/patch/802608/
>>
>
> In that case maybe you should use the disable_locking option in
> regmap_config and provide your own callbacks that you can use in the
> irqchip code too?

But how would that solve problem (1). And keep in mind, that the
reqmap_irqchip is actually used for the interrupt controller, which
is not this gpio controller.

Ie. the interrupt controller of the sl28cpld uses the regmap_irqchip
and all interrupt phandles pointing to the interrupt controller will
reference the toplevel node. Any phandles pointing to the gpio
controller will reference the GPIO subnode.

>
>> >
>> >> +}
>> >> +
>> >> +static void sl28cpld_gpio_irq_sync_unlock(struct irq_data *data)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio =
>> >> + gpiochip_get_data(irq_data_get_irq_chip_data(data));
>> >> +
>> >> + regmap_write(gpio->regmap, gpio->offset + GPIO_REG_IE,
>> >> gpio->ie);
>> >> + mutex_unlock(&gpio->lock);
>> >> +}
>> >> +
>> >> +static void sl28cpld_gpio_irq_disable(struct irq_data *data)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio =
>> >> + gpiochip_get_data(irq_data_get_irq_chip_data(data));
>> >> +
>> >> + if (data->hwirq >= 8)
>> >> + return;
>> >> +
>> >> + gpio->ie &= ~(1 << data->hwirq);
>> >> +}
>> >> +
>> >> +static void sl28cpld_gpio_irq_enable(struct irq_data *data)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio =
>> >> + gpiochip_get_data(irq_data_get_irq_chip_data(data));
>> >> +
>> >> + if (data->hwirq >= 8)
>> >> + return;
>> >> +
>> >> + gpio->ie |= (1 << data->hwirq);
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpio_irq_set_type(struct irq_data *data, unsigned
>> >> int type)
>> >> +{
>> >> + /* only edge triggered interrupts on both edges are supported
>> >> */
>> >> + return (type == IRQ_TYPE_EDGE_BOTH) ? 0 : -EINVAL;
>> >> +}
>> >> +
>> >> +static irqreturn_t sl28cpld_gpio_irq_thread(int irq, void *data)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio = data;
>> >> + unsigned int ip;
>> >> + unsigned int virq;
>> >> + int pin;
>> >> + int ret;
>> >> +
>> >> + ret = regmap_read(gpio->regmap, gpio->offset + GPIO_REG_IP,
>> >> &ip);
>> >> + if (ret)
>> >> + return IRQ_NONE;
>> >> +
>> >> + /* mask other pending interrupts which are not enabled */
>> >> + ip &= gpio->ie;
>> >> +
>> >> + /* ack the interrupts */
>> >> + regmap_write(gpio->regmap, gpio->offset + GPIO_REG_IP, ip);
>> >> +
>> >> + /* and handle them */
>> >> + while (ip) {
>> >> + pin = __ffs(ip);
>> >> + ip &= ~BIT(pin);
>> >> +
>> >> + virq = irq_find_mapping(gpio->gpio_chip.irq.domain,
>> >> pin);
>> >> + if (virq)
>> >> + handle_nested_irq(virq);
>> >> + }
>> >> +
>> >> + return IRQ_HANDLED;
>> >> +}
>> >
>> > This definitely looks like parts of regmap_irqchip reimplemented.
>> > Please check if you could reuse it - it would save a lot of code.
>>
>> See above. I'd be happy to reuse the code though.
>>
>> >
>> >> +
>> >> +static int sl28_cpld_gpio_irq_init(struct platform_device *pdev, int
>> >> irq)
>> >> +{
>> >> + struct sl28cpld_gpio *gpio = platform_get_drvdata(pdev);
>> >> + struct irq_chip *irq_chip = &gpio->irq_chip;
>> >> + int ret;
>> >> +
>> >> + irq_chip->name = "sl28cpld-gpio-irq",
>> >> + irq_chip->irq_bus_lock = sl28cpld_gpio_irq_lock,
>> >> + irq_chip->irq_bus_sync_unlock = sl28cpld_gpio_irq_sync_unlock,
>> >> + irq_chip->irq_disable = sl28cpld_gpio_irq_disable,
>> >> + irq_chip->irq_enable = sl28cpld_gpio_irq_enable,
>> >> + irq_chip->irq_set_type = sl28cpld_gpio_irq_set_type,
>> >> + irq_chip->flags = IRQCHIP_SKIP_SET_WAKE,
>> >> +
>> >> + ret = gpiochip_irqchip_add_nested(&gpio->gpio_chip, irq_chip,
>> >> 0,
>> >> + handle_simple_irq,
>> >> IRQ_TYPE_NONE);
>> >> + if (ret)
>> >> + return ret;
>> >> +
>> >> + ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
>> >> + sl28cpld_gpio_irq_thread,
>> >> + IRQF_SHARED | IRQF_ONESHOT,
>> >> + pdev->name, gpio);
>> >> + if (ret)
>> >> + return ret;
>> >> +
>> >> + gpiochip_set_nested_irqchip(&gpio->gpio_chip, irq_chip, irq);
>> >> +
>> >> + return 0;
>> >> +}
>> >> +
>> >> +static int sl28cpld_gpio_probe(struct platform_device *pdev)
>> >> +{
>> >> + enum sl28cpld_gpio_type type =
>> >> + platform_get_device_id(pdev)->driver_data;
>> >> + struct device_node *np = pdev->dev.of_node;
>> >> + struct sl28cpld_gpio *gpio;
>> >> + struct gpio_chip *chip;
>> >> + struct resource *res;
>> >> + bool irq_support = false;
>> >> + int ret;
>> >> + int irq;
>> >> +
>> >> + gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
>> >> + if (!gpio)
>> >> + return -ENOMEM;
>> >> +
>> >> + if (!pdev->dev.parent)
>> >> + return -ENODEV;
>> >
>> > Why not check this before allocating any memory?
>>
>> I'll change that, you're not the first one which notices that. My
>> reason
>> was to have the check together with the dev_get_regmap() which uses
>> the
>> parent, expecting that the error case only happen exceptionally.
>>
>> >
>> >> +
>> >> + gpio->regmap = dev_get_regmap(pdev->dev.parent, NULL);
>> >> + if (!gpio->regmap)
>> >> + return -ENODEV;
>> >> +
>> >> + res = platform_get_resource(pdev, IORESOURCE_REG, 0);
>> >> + if (!res)
>> >> + return -EINVAL;
>> >> + gpio->offset = res->start;
>> >> +
>> >
>> > This isn't how IO resources are used. What are you trying to achieve
>> > here?
>>
>> Mh are you sure? The blueprint for this were the regulators in
>> drivers/regulators/, eg the wm831x-ldo.c. IORESOURCE_REG isn't used
>> that often. But here is what I want to achieve (for which I haven't
>> found any existing drivers for now):
>> (1) the individual blocks of the overall sl28cpld may be used
>> multiple times, eg. this driver only has the offset to a
>> base address. So if there are two blocks, this mfd core
>> driver will register two devices for this driver with
>> different base offsets, which are passed by IORESOURCE_REG
>> (2) I wanted to avoid having a private mfd include with some
>> kind of "proprietary" method how to get that offset
>> (3) the mfd core driver is the one knowing the offset, thus it
>> is possible to have different flavours of the sl28cpld
>>
>
> Ok, now I see it's documented in the bindings. Thanks for the
> explanation.
>
>>
>> >
>> >> + /* initialize struct gpio_chip */
>> >> + mutex_init(&gpio->lock);
>> >> + chip = &gpio->gpio_chip;
>> >> + chip->parent = &pdev->dev;
>> >> + chip->label = dev_name(&pdev->dev);
>> >> + chip->owner = THIS_MODULE;
>> >> + chip->can_sleep = true;
>> >> + chip->base = -1;
>> >> + chip->ngpio = 8;
>> >> +
>> >> + switch (type) {
>> >> + case sl28cpld_gpio:
>> >> + chip->get_direction = sl28cpld_gpio_get_direction;
>> >> + chip->direction_input = sl28cpld_gpio_direction_input;
>> >> + chip->direction_output =
>> >> sl28cpld_gpio_direction_output;
>> >> + chip->get = sl28cpld_gpio_get;
>> >> + chip->set = sl28cpld_gpio_set;
>> >> + irq_support = true;
>> >> + break;
>> >> + case sl28cpld_gpo:
>> >> + chip->set = sl28cpld_gpo_set;
>> >> + chip->get = sl28cpld_gpi_get;
>> >> + break;
>> >> + case sl28cpld_gpi:
>> >> + chip->get = sl28cpld_gpi_get;
>> >> + break;
>> >> + }
>> >> +
>> >> + ret = devm_gpiochip_add_data(&pdev->dev, chip, gpio);
>> >> + if (ret < 0)
>> >> + return ret;
>> >> +
>> >> + platform_set_drvdata(pdev, gpio);
>> >> +
>> >> + if (irq_support && of_property_read_bool(np,
>> >> "interrupt-controller")) {
>> >
>> > You're depending on OF_GPIO for this one function. Please switch to
>> > device_property_read_bool() instead.
>>
>> ok
>>
>>
>> >
>> >> + irq = platform_get_irq(pdev, 0);
>> >> + if (irq < 0)
>> >> + return ret;
>> >> +
>> >> + ret = sl28_cpld_gpio_irq_init(pdev, irq);
>> >> + if (ret)
>> >> + return ret;
>> >> + }
>> >> +
>> >> + return 0;
>> >> +}
>> >> +
>> >> +static const struct platform_device_id sl28cpld_gpio_id_table[] = {
>> >> + {"sl28cpld-gpio", sl28cpld_gpio},
>> >> + {"sl28cpld-gpi", sl28cpld_gpi},
>> >> + {"sl28cpld-gpo", sl28cpld_gpo},
>> >
>> > Could you explain this a bit more? Is this the same component with
>> > input/output-only lines or three different components?
>>
>> These are actually three different components. Ie. you could have a
>> flavour where you have one GPIO (sl28cpld-gpio) and two output-only
>> ones (sl28cpld-gpo). Is that what you wanted to know?
>>
>
> Yes, thanks. This could use some documentation in the bindings though.

ok. thats easy ;)

-michael

> Bartosz
>
>> >
>> >> +};
>> >> +MODULE_DEVICE_TABLE(platform, sl28cpld_gpio_id_table);
>> >> +
>> >> +static struct platform_driver sl28cpld_gpio_driver = {
>> >> + .probe = sl28cpld_gpio_probe,
>> >> + .id_table = sl28cpld_gpio_id_table,
>> >> + .driver = {
>> >> + .name = "sl28cpld-gpio",
>> >> + },
>> >> +};
>> >> +module_platform_driver(sl28cpld_gpio_driver);
>> >> +
>> >> +MODULE_DESCRIPTION("sl28cpld GPIO Driver");
>> >> +MODULE_LICENSE("GPL");
>> >
>> > I think you could use a MODULE_ALIAS() here if you want this module to
>> > be loaded automatically by udev.
>>
>> ok, I'll look into that.
>>
>> thanks,
>> -michael
>>
>> >
>> >> --
>> >> 2.20.1
>> >>
>> >
>> > Best regards,
>> > Bartosz Golaszewski

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