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Message-Id: <20230608162130.55015-1-andriy.shevchenko@linux.intel.com>
Date: Thu, 8 Jun 2023 19:21:30 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Geert Uytterhoeven <geert+renesas@...der.be>,
Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <brgl@...ev.pl>,
Andy Shevchenko <andy@...nel.org>,
Alexander Stein <linux@...tq-group.com>
Subject: [rfc, rft, PATCH v1 1/1] gpio: aggregator: Introduce delay support for individual output pins
The aggregator mode can also handle properties of the platform, that
do not belong to the GPIO controller itself. One of such a property
is signal delay line. Intdoduce support of it.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
I don't like the idea of gpio-delay or similar. We have already GPIO
aggregator that incorporates the GPIO proxy / forwarder functionality.
This one is RFC because:
1) just compile tested;
2) has obvious issues with CONFIG_OF_GPIO;
3) contains ~5 patches in a single change for now;
4) requires additional work with blocking sysfs for this;
5) requires some DT bindings work;
6) ...whatever I forgot...
Any comments are appreciated, and tests are esp. welcome!
drivers/gpio/gpio-aggregator.c | 84 ++++++++++++++++++++++++++++++----
1 file changed, 74 insertions(+), 10 deletions(-)
diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
index 20a686f12df7..802d123f0188 100644
--- a/drivers/gpio/gpio-aggregator.c
+++ b/drivers/gpio/gpio-aggregator.c
@@ -10,12 +10,14 @@
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/ctype.h>
+#include <linux/delay.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/overflow.h>
#include <linux/platform_device.h>
+#include <linux/property.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
@@ -239,6 +241,11 @@ static void __exit gpio_aggregator_remove_all(void)
* GPIO Forwarder
*/
+struct gpiochip_fwd_timing {
+ unsigned long ramp_up_us;
+ unsigned long ramp_down_us;
+};
+
struct gpiochip_fwd {
struct gpio_chip chip;
struct gpio_desc **descs;
@@ -246,6 +253,7 @@ struct gpiochip_fwd {
struct mutex mlock; /* protects tmp[] if can_sleep */
spinlock_t slock; /* protects tmp[] if !can_sleep */
};
+ struct gpiochip_fwd_timing *delay_timings;
unsigned long tmp[]; /* values and descs for multiple ops */
};
@@ -333,11 +341,28 @@ static int gpio_fwd_get_multiple_locked(struct gpio_chip *chip,
static void gpio_fwd_set(struct gpio_chip *chip, unsigned int offset, int value)
{
struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+ const struct gpiochip_fwd_timing *delay_timings;
+ struct gpio_desc *desc = fwd->descs[offset];
+ bool is_active_low = gpiod_is_active_low(desc);
+ bool ramp_up;
- if (chip->can_sleep)
- gpiod_set_value_cansleep(fwd->descs[offset], value);
- else
- gpiod_set_value(fwd->descs[offset], value);
+ delay_timings = &fwd->delay_timings[offset];
+ ramp_up = (!is_active_low && value) || (is_active_low && !value);
+ if (chip->can_sleep) {
+ gpiod_set_value_cansleep(desc, value);
+
+ if (ramp_up && delay_timings->ramp_up_us)
+ fsleep(delay_timings->ramp_up_us);
+ if (!ramp_up && delay_timings->ramp_down_us)
+ fsleep(delay_timings->ramp_down_us);
+ } else {
+ gpiod_set_value(desc, value);
+
+ if (ramp_up && delay_timings->ramp_up_us)
+ udelay(delay_timings->ramp_up_us);
+ if (!ramp_up && delay_timings->ramp_down_us)
+ udelay(delay_timings->ramp_down_us);
+ }
}
static void gpio_fwd_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
@@ -390,6 +415,28 @@ static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset)
return gpiod_to_irq(fwd->descs[offset]);
}
+static int gpiochip_fwd_delay_of_xlate(struct gpio_chip *chip,
+ const struct of_phandle_args *gpiospec,
+ u32 *flags)
+{
+ struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+ struct gpiochip_fwd_timing *timings;
+ u32 line;
+
+ if (gpiospec->args_count != chip->of_gpio_n_cells)
+ return -EINVAL;
+
+ line = gpiospec->args[0];
+ if (line >= chip->ngpio)
+ return -EINVAL;
+
+ timings = &fwd->delay_timings[line];
+ timings->ramp_up_us = gpiospec->args[1];
+ timings->ramp_down_us = gpiospec->args[2];
+
+ return line;
+}
+
/**
* gpiochip_fwd_create() - Create a new GPIO forwarder
* @dev: Parent device pointer
@@ -397,6 +444,7 @@ static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset)
* @descs: Array containing the GPIO descriptors to forward to.
* This array must contain @ngpios entries, and must not be deallocated
* before the forwarder has been destroyed again.
+ * @delay: True if the pins have an external delay line.
*
* This function creates a new gpiochip, which forwards all GPIO operations to
* the passed GPIO descriptors.
@@ -406,7 +454,8 @@ static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset)
*/
static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
unsigned int ngpios,
- struct gpio_desc *descs[])
+ struct gpio_desc *descs[],
+ bool delay)
{
const char *label = dev_name(dev);
struct gpiochip_fwd *fwd;
@@ -459,6 +508,17 @@ static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
else
spin_lock_init(&fwd->slock);
+ if (delay) {
+ fwd->delay_timings = devm_kcalloc(dev, ngpios,
+ sizeof(*fwd->delay_timings),
+ GFP_KERNEL);
+ if (!fwd->delay_timings)
+ return ERR_PTR(-ENOMEM);
+
+ chip->of_xlate = gpiochip_fwd_delay_of_xlate;
+ chip->of_gpio_n_cells = 3;
+ }
+
error = devm_gpiochip_add_data(dev, chip, fwd);
if (error)
return ERR_PTR(error);
@@ -476,6 +536,7 @@ static int gpio_aggregator_probe(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct gpio_desc **descs;
struct gpiochip_fwd *fwd;
+ bool delay;
int i, n;
n = gpiod_count(dev, NULL);
@@ -492,7 +553,9 @@ static int gpio_aggregator_probe(struct platform_device *pdev)
return PTR_ERR(descs[i]);
}
- fwd = gpiochip_fwd_create(dev, n, descs);
+ delay = fwnode_device_is_compatible(dev_fwnode(dev), "gpio-delay");
+
+ fwd = gpiochip_fwd_create(dev, n, descs, delay);
if (IS_ERR(fwd))
return PTR_ERR(fwd);
@@ -500,23 +563,24 @@ static int gpio_aggregator_probe(struct platform_device *pdev)
return 0;
}
-#ifdef CONFIG_OF
static const struct of_device_id gpio_aggregator_dt_ids[] = {
/*
* Add GPIO-operated devices controlled from userspace below,
- * or use "driver_override" in sysfs
+ * or use "driver_override" in sysfs.
*/
+ {
+ .compatible = "gpio-delay",
+ },
{}
};
MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids);
-#endif
static struct platform_driver gpio_aggregator_driver = {
.probe = gpio_aggregator_probe,
.driver = {
.name = DRV_NAME,
.groups = gpio_aggregator_groups,
- .of_match_table = of_match_ptr(gpio_aggregator_dt_ids),
+ .of_match_table = gpio_aggregator_dt_ids,
},
};
--
2.40.0.1.gaa8946217a0b
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