On Thu, 2012-11-01 at 17:58 +0000, Pawel Moll wrote:
> LEDs are often controlled by writing to memory mapped
> register. This patch adds:
>
> 1. Generic functions for platform code and drivers to create
> class device for LEDs controlled by arbitrary bit masks.
> The control register value is read, modified by logic AND
> and OR operations with respective mask and written back.
>
> 2. A platform driver for simple use case when one or more LED
> are controlled by consecutive bits in a register pointed
> at by the platform device's memory resource. It can be
> particularly useful for MFD cells being part of an other
> device.
>
> Signed-off-by: Pawel Moll <pawel.m...@arm.com>
> ---
> drivers/leds/Kconfig | 8 ++
> drivers/leds/Makefile | 1 +
> drivers/leds/leds-mmio.c | 250
> ++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/leds.h | 38 +++++++
> 4 files changed, 297 insertions(+)
> create mode 100644 drivers/leds/leds-mmio.c
>
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index f508def..93707e6 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -457,6 +457,14 @@ config LEDS_BLINKM
> This option enables support for the BlinkM RGB LED connected
> through I2C. Say Y to enable support for the BlinkM LED.
>
> +config LEDS_MMIO
> + tristate "Generic LED support for memory mapped peripherals"
> + depends on LEDS_CLASS
> + depends on HAS_IOMEM
> + help
> + This option enables generic support for LEDs controlled via
> + memory mapped registers.
> +
> config LEDS_TRIGGERS
> bool "LED Trigger support"
> depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 3fb9641..8e5d0c8 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -51,6 +51,7 @@ obj-$(CONFIG_LEDS_RENESAS_TPU) +=
> leds-renesas-tpu.o
> obj-$(CONFIG_LEDS_MAX8997) += leds-max8997.o
> obj-$(CONFIG_LEDS_LM355x) += leds-lm355x.o
> obj-$(CONFIG_LEDS_BLINKM) += leds-blinkm.o
> +obj-$(CONFIG_LEDS_MMIO) += leds-mmio.o
>
> # LED SPI Drivers
> obj-$(CONFIG_LEDS_DAC124S085) += leds-dac124s085.o
> diff --git a/drivers/leds/leds-mmio.c b/drivers/leds/leds-mmio.c
> new file mode 100644
> index 0000000..1ef0cda
> --- /dev/null
> +++ b/drivers/leds/leds-mmio.c
> @@ -0,0 +1,250 @@
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * Copyright (C) 2012 ARM Limited
> + */
> +
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/mfd/core.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +
> +static u32 mmio_led_read(void __iomem *reg, unsigned reg_size)
> +{
> + switch (reg_size) {
> + case 32:
> + return readl(reg);
> + case 16:
> + return readw(reg);
> + case 8:
> + return readb(reg);
> + }
> + return 0;
> +}
> +
> +static void mmio_led_write(void __iomem *reg, unsigned reg_size, u32 val)
> +{
> + switch (reg_size) {
> + case 32:
> + writel(val, reg);
> + return;
> + case 16:
> + writew(val, reg);
> + return;
> + case 8:
> + writeb(val, reg);
> + return;
> + }
> +}
> +
> +
> +struct mmio_led {
> + struct led_classdev cdev;
> + spinlock_t *lock;
> + void __iomem *reg;
> + unsigned reg_size;
> + u32 off_and_mask, off_or_mask;
> + u32 on_and_mask, on_or_mask;
> +};
> +
> +static void mmio_led_brightness_set(struct led_classdev *cdev,
> + enum led_brightness brightness)
> +{
> + struct mmio_led *led = container_of(cdev, struct mmio_led, cdev);
> + unsigned long uninitialized_var(flags);
uninitialized_var seems to be a bit contentious, Linus Torvalds had a
recent complaint about it which prompted Ingo to post a patch proposing
to removing it: https://patchwork.kernel.org/patch/1655621/ So perhaps
best to avoid using it ;-).
In this case, you could possibly keep gcc quite with something like:
spinlock_t *lock = led->lock;
and then use the local variable 'lock' everywhere instead of led->lock.
Or just keep it simple an initialise flags to 0 instead.
> + u32 val;
> +
> + if (led->lock)
> + spin_lock_irqsave(led->lock, flags);
> +
> + val = mmio_led_read(led->reg, led->reg_size);
> + if (brightness == LED_OFF) {
> + val &= led->off_and_mask;
> + val |= led->off_or_mask;
> + } else {
> + val &= led->on_and_mask;
> + val |= led->on_or_mask;
> + }
> + mmio_led_write(led->reg, led->reg_size, val);
> +
> + if (led->lock)
> + spin_unlock_irqrestore(led->lock, flags);
> +};
> +
> +static enum led_brightness mmio_led_brightness_get(struct led_classdev *cdev)
> +{
> + struct mmio_led *led = container_of(cdev, struct mmio_led, cdev);
> + unsigned long uninitialized_var(flags);
Same comment as previous.
> + u32 val;
> +
> + if (led->lock)
> + spin_lock_irqsave(led->lock, flags);
> + val = mmio_led_read(led->reg, led->reg_size);
> + if (led->lock)
> + spin_unlock_irqrestore(led->lock, flags);
> +
> + if (((val & led->on_and_mask) | led->on_or_mask) == val)
> + return LED_FULL;
> + else
> + return LED_OFF;
> +}
> +
> +struct mmio_led *mmio_led_register(struct device *parent, spinlock_t *lock,
> + const char *name, const char *default_trigger,
> + void __iomem *reg, unsigned reg_size, u32 off_and_mask,
> + u32 off_or_mask, u32 on_and_mask, u32 on_or_mask)
> +{
> + struct mmio_led *led;
> + int err;
> +
> + if (WARN_ON(reg_size != 8 && reg_size != 16 && reg_size != 32))
> + return ERR_PTR(-EINVAL);
> +
> + led = kzalloc(sizeof(*led), GFP_KERNEL);
> + if (!led)
> + return ERR_PTR(-ENOMEM);
> +
> + led->cdev.brightness_set = mmio_led_brightness_set;
> + led->cdev.brightness_get = mmio_led_brightness_get;
> + led->cdev.name = name;
> + led->cdev.default_trigger = default_trigger;
> +
> + led->lock = lock;
> + led->reg = reg;
> + led->reg_size = reg_size;
> + led->off_and_mask = off_and_mask;
> + led->off_or_mask = off_or_mask;
> + led->on_and_mask = on_and_mask;
> + led->on_or_mask = on_or_mask;
> +
> + err = led_classdev_register(parent, &led->cdev);
> + if (err) {
> + kfree(led);
> + return ERR_PTR(err);
> + }
> +
> + return led;
> +}
> +EXPORT_SYMBOL_GPL(mmio_led_register);
> +
> +void mmio_led_unregister(struct mmio_led *led)
> +{
> + led_classdev_unregister(&led->cdev);
> + kfree(led);
> +}
> +EXPORT_SYMBOL_GPL(mmio_led_unregister);
> +
> +
> +struct mmio_simple_leds {
> + spinlock_t lock;
> + int num_leds;
> + struct mmio_led *leds[0];
> +};
> +
> +static int __devinit mmio_simple_leds_probe(struct platform_device *pdev)
> +{
> + struct mmio_simple_leds_platform_data *pdata = pdev->dev.platform_data;
> + struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + struct mmio_simple_leds *leds;
> + void __iomem *reg;
> + u32 val, mask;
> + int i;
> +
> + if (!pdata)
> + return -EINVAL;
> +
> + if (pdata->reg_size != 8 && pdata->reg_size != 16 &&
> + pdata->reg_size != 32)
> + return -EFAULT;
Is EFAULT appropriate here? Why not EINVAL?
> + leds = devm_kzalloc(&pdev->dev, sizeof(*leds) +
> + sizeof(leds->leds) * pdata->width, GFP_KERNEL);
> + if (!leds)
> + return -ENOMEM;
> + spin_lock_init(&leds->lock);
> +
> + if ((!pdev->mfd_cell || !pdev->mfd_cell->ignore_resource_conflicts) &&
> + !devm_request_mem_region(&pdev->dev, res->start,
> + resource_size(res), pdev->name))
> + return -EBUSY;
> +
> + reg = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> + if (!reg)
> + return -ENOMEM;
> +
> + val = mmio_led_read(reg, pdata->reg_size);
> + mask = ((1 << pdata->width) - 1) << pdata->shift;
> + if ((pdata->init_full && pdata->active_low) ||
> + (pdata->init_off && !pdata->active_low))
> + val &= ~mask;
> + else if ((pdata->init_off && pdata->active_low) ||
> + (pdata->init_full && !pdata->active_low))
> + val |= mask;
> + mmio_led_write(reg, pdata->reg_size, val);
> +
> + leds->num_leds = pdata->width;
> + for (i = 0; i < leds->num_leds; i++) {
> + unsigned shift = pdata->shift + i;
> + u32 and_mask = ~BIT(shift);
> + u32 off_or_mask = pdata->active_low ? BIT(shift) : 0;
> + u32 on_or_mask = pdata->active_low ? 0 : BIT(shift);
> + struct mmio_led *led = mmio_led_register(&pdev->dev,
> + &leds->lock, pdata->names[i],
> + pdata->default_triggers ?
> + pdata->default_triggers[i] : NULL,
> + reg, pdata->reg_size, and_mask, off_or_mask,
> + and_mask, on_or_mask);
> +
> + if (IS_ERR(led)) {
> + while (--i >= 0)
> + mmio_led_unregister(leds->leds[i]);
> + return PTR_ERR(led);
> + }
> + leds->leds[i] = led;
> + }
> +
> + platform_set_drvdata(pdev, leds);
> +
> + return 0;
> +}
> +
> +static int __devexit mmio_simple_leds_remove(struct platform_device *pdev)
> +{
> + struct mmio_simple_leds *leds = platform_get_drvdata(pdev);
> + int i;
> +
> + platform_set_drvdata(pdev, NULL);
> +
> + for (i = 0; i < leds->num_leds; i++)
> + mmio_led_unregister(leds->leds[i]);
> +
> + return 0;
> +}
> +
> +static struct platform_driver mmio_simple_leds_driver = {
> + .probe = mmio_simple_leds_probe,
> + .remove = __devexit_p(mmio_simple_leds_remove),
> + .driver = {
> + .name = "leds-mmio-simple",
> + .owner = THIS_MODULE,
> + },
> +};
> +
> +module_platform_driver(mmio_simple_leds_driver);
> +
> +MODULE_AUTHOR("Pawel Moll <pawel.m...@arm.com>");
> +MODULE_DESCRIPTION("MMIO LED driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:leds-mmio-simple");
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 6e53bb3..a6338b0 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -241,6 +241,44 @@ struct gpio_led_platform_data {
> struct platform_device *gpio_led_register_device(
> int id, const struct gpio_led_platform_data *pdata);
>
> +/* For the leds-mmio driver */
> +
> +struct mmio_led;
> +
> +#if defined(CONFIG_LEDS_MMIO)
> +/* Returns ERR_PTR in case of error */
> +struct mmio_led *mmio_led_register(struct device *parent, spinlock_t *lock,
> + const char *name, const char *default_trigger,
> + void __iomem *reg, unsigned reg_size, u32 off_and_mask,
> + u32 off_or_mask, u32 on_and_mask, u32 on_or_mask);
> +void mmio_led_unregister(struct mmio_led *led);
> +#else
> +struct mmio_led *mmio_led_register(struct device *parent, spinlock_t *lock,
> + const char *name, const char *default_trigger,
> + void __iomem *reg, unsigned reg_size, u32 off_and_mask,
> + u32 off_or_mask, u32 on_and_mask, u32 on_or_mask)
> +{
> + return NULL;
> +}
> +
> +void mmio_led_unregister(struct mmio_led *led)
> +{
> +}
> +#endif
> +
> +struct mmio_simple_leds_platform_data {
> + unsigned reg_size; /* Register size (8/16/32) */
> + unsigned shift; /* First bit controlling LEDs */
> + unsigned width; /* Number of consecutive bits */
> + const char **names; /* Must define 'width' names */
> + const char **default_triggers; /* NULL or 'width' strings */
> + bool active_low;
> + bool init_full;
> + bool init_off;
> +};
> +
> +/* CPU led trigger */
> +
> enum cpu_led_event {
> CPU_LED_IDLE_START, /* CPU enters idle */
> CPU_LED_IDLE_END, /* CPU idle ends */
--
Tixy
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