Commit f23f1516 authored by Shiraz Hashim's avatar Shiraz Hashim Committed by Linus Walleij

gpiolib: provide provision to register pin ranges

pinctrl subsystem needs gpio chip base to prepare set of gpio
pin ranges, which a given pinctrl driver can handle. This is
important to handle pinctrl gpio request calls in order to
program a given pin properly for gpio operation.

As gpio base is allocated dynamically during gpiochip
registration, presently there exists no clean way to pass this
information to the pinctrl subsystem.

After few discussions from [1], it was concluded that may be
gpio controller reporting the pin range it supports, is a
better way than pinctrl subsystem directly registering it.

[1] http://comments.gmane.org/gmane.linux.ports.arm.kernel/184816

Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarShiraz Hashim <shiraz.hashim@st.com>
[Edited documentation a bit]
Signed-off-by: Linus Walleij's avatarLinus Walleij <linus.walleij@linaro.org>
parent 7e10ee68
......@@ -75,4 +75,40 @@ Example of two SOC GPIO banks defined as gpio-controller nodes:
gpio-controller;
};
2.1) gpio-controller and pinctrl subsystem
------------------------------------------
gpio-controller on a SOC might be tightly coupled with the pinctrl
subsystem, in the sense that the pins can be used by other functions
together with optional gpio feature.
While the pin allocation is totally managed by the pin ctrl subsystem,
gpio (under gpiolib) is still maintained by gpio drivers. It may happen
that different pin ranges in a SoC is managed by different gpio drivers.
This makes it logical to let gpio drivers announce their pin ranges to
the pin ctrl subsystem and call 'pinctrl_request_gpio' in order to
request the corresponding pin before any gpio usage.
For this, the gpio controller can use a pinctrl phandle and pins to
announce the pinrange to the pin ctrl subsystem. For example,
qe_pio_e: gpio-controller@1460 {
#gpio-cells = <2>;
compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
reg = <0x1460 0x18>;
gpio-controller;
gpio-ranges = <&pinctrl1 20 10>, <&pinctrl2 50 20>;
}
where,
&pinctrl1 and &pinctrl2 is the phandle to the pinctrl DT node.
Next values specify the base pin and number of pins for the range
handled by 'qe_pio_e' gpio. In the given example from base pin 20 to
pin 29 under pinctrl1 and pin 50 to pin 69 under pinctrl2 is handled
by this gpio controller.
The pinctrl node must have "#gpio-range-cells" property to show number of
arguments to pass with phandle from gpio controllers node.
......@@ -439,6 +439,48 @@ slower clock delays the rising edge of SCK, and the I2C master adjusts its
signaling rate accordingly.
GPIO controllers and the pinctrl subsystem
------------------------------------------
A GPIO controller on a SOC might be tightly coupled with the pinctrl
subsystem, in the sense that the pins can be used by other functions
together with an optional gpio feature. We have already covered the
case where e.g. a GPIO controller need to reserve a pin or set the
direction of a pin by calling any of:
pinctrl_request_gpio()
pinctrl_free_gpio()
pinctrl_gpio_direction_input()
pinctrl_gpio_direction_output()
But how does the pin control subsystem cross-correlate the GPIO
numbers (which are a global business) to a certain pin on a certain
pin controller?
This is done by registering "ranges" of pins, which are essentially
cross-reference tables. These are described in
Documentation/pinctrl.txt
While the pin allocation is totally managed by the pinctrl subsystem,
gpio (under gpiolib) is still maintained by gpio drivers. It may happen
that different pin ranges in a SoC is managed by different gpio drivers.
This makes it logical to let gpio drivers announce their pin ranges to
the pin ctrl subsystem before it will call 'pinctrl_request_gpio' in order
to request the corresponding pin to be prepared by the pinctrl subsystem
before any gpio usage.
For this, the gpio controller can register its pin range with pinctrl
subsystem. There are two ways of doing it currently: with or without DT.
For with DT support refer to Documentation/devicetree/bindings/gpio/gpio.txt.
For non-DT support, user can call gpiochip_add_pin_range() with appropriate
parameters to register a range of gpio pins with a pinctrl driver. For this
exact name string of pinctrl device has to be passed as one of the
argument to this routine.
What do these conventions omit?
===============================
One of the biggest things these conventions omit is pin multiplexing, since
......
......@@ -364,6 +364,9 @@ will get an pin number into its handled number range. Further it is also passed
the range ID value, so that the pin controller knows which range it should
deal with.
Calling pinctrl_add_gpio_range from pinctrl driver is DEPRECATED. Please see
section 2.1 of Documentation/devicetree/bindings/gpio/gpio.txt on how to bind
pinctrl and gpio drivers.
PINMUX interfaces
=================
......
......@@ -19,6 +19,7 @@
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_gpio.h>
#include <linux/pinctrl/pinctrl.h>
#include <linux/slab.h>
/* Private data structure for of_gpiochip_find_and_xlate */
......@@ -216,6 +217,58 @@ int of_mm_gpiochip_add(struct device_node *np,
}
EXPORT_SYMBOL(of_mm_gpiochip_add);
#ifdef CONFIG_PINCTRL
void of_gpiochip_add_pin_range(struct gpio_chip *chip)
{
struct device_node *np = chip->of_node;
struct gpio_pin_range *pin_range;
struct of_phandle_args pinspec;
int index = 0, ret;
if (!np)
return;
do {
ret = of_parse_phandle_with_args(np, "gpio-ranges",
"#gpio-range-cells", index, &pinspec);
if (ret)
break;
pin_range = devm_kzalloc(chip->dev, sizeof(*pin_range),
GFP_KERNEL);
if (!pin_range) {
pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
chip->label);
break;
}
pin_range->range.name = chip->label;
pin_range->range.base = chip->base;
pin_range->range.pin_base = pinspec.args[0];
pin_range->range.npins = pinspec.args[1];
pin_range->pctldev = of_pinctrl_add_gpio_range(pinspec.np,
&pin_range->range);
list_add_tail(&pin_range->node, &chip->pin_ranges);
} while (index++);
}
void of_gpiochip_remove_pin_range(struct gpio_chip *chip)
{
struct gpio_pin_range *pin_range, *tmp;
list_for_each_entry_safe(pin_range, tmp, &chip->pin_ranges, node) {
list_del(&pin_range->node);
pinctrl_remove_gpio_range(pin_range->pctldev,
&pin_range->range);
}
}
#else
void of_gpiochip_add_pin_range(struct gpio_chip *chip) {}
void of_gpiochip_remove_pin_range(struct gpio_chip *chip) {}
#endif
void of_gpiochip_add(struct gpio_chip *chip)
{
if ((!chip->of_node) && (chip->dev))
......@@ -229,11 +282,14 @@ void of_gpiochip_add(struct gpio_chip *chip)
chip->of_xlate = of_gpio_simple_xlate;
}
of_gpiochip_add_pin_range(chip);
of_node_get(chip->of_node);
}
void of_gpiochip_remove(struct gpio_chip *chip)
{
of_gpiochip_remove_pin_range(chip);
if (chip->of_node)
of_node_put(chip->of_node);
}
......@@ -1083,6 +1083,10 @@ int gpiochip_add(struct gpio_chip *chip)
}
}
#ifdef CONFIG_PINCTRL
INIT_LIST_HEAD(&chip->pin_ranges);
#endif
of_gpiochip_add(chip);
unlock:
......@@ -1180,6 +1184,45 @@ struct gpio_chip *gpiochip_find(void *data,
}
EXPORT_SYMBOL_GPL(gpiochip_find);
#ifdef CONFIG_PINCTRL
void gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
unsigned int pin_base, unsigned int npins)
{
struct gpio_pin_range *pin_range;
pin_range = devm_kzalloc(chip->dev, sizeof(*pin_range), GFP_KERNEL);
if (!pin_range) {
pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
chip->label);
return;
}
pin_range->range.name = chip->label;
pin_range->range.base = chip->base;
pin_range->range.pin_base = pin_base;
pin_range->range.npins = npins;
pin_range->pctldev = find_pinctrl_and_add_gpio_range(pinctl_name,
&pin_range->range);
list_add_tail(&pin_range->node, &chip->pin_ranges);
}
void gpiochip_remove_pin_ranges(struct gpio_chip *chip)
{
struct gpio_pin_range *pin_range, *tmp;
list_for_each_entry_safe(pin_range, tmp, &chip->pin_ranges, node) {
list_del(&pin_range->node);
pinctrl_remove_gpio_range(pin_range->pctldev,
&pin_range->range);
}
}
#else
void gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
unsigned int pin_base, unsigned int npins) {}
void gpiochip_remove_pin_ranges(struct gpio_chip *chip) {}
#endif
/* These "optional" allocation calls help prevent drivers from stomping
* on each other, and help provide better diagnostics in debugfs.
* They're called even less than the "set direction" calls.
......
......@@ -345,6 +345,19 @@ void pinctrl_add_gpio_ranges(struct pinctrl_dev *pctldev,
}
EXPORT_SYMBOL_GPL(pinctrl_add_gpio_ranges);
struct pinctrl_dev *find_pinctrl_and_add_gpio_range(const char *devname,
struct pinctrl_gpio_range *range)
{
struct pinctrl_dev *pctldev = get_pinctrl_dev_from_devname(devname);
if (!pctldev)
return NULL;
pinctrl_add_gpio_range(pctldev, range);
return pctldev;
}
EXPORT_SYMBOL_GPL(find_pinctrl_and_add_gpio_range);
/**
* pinctrl_remove_gpio_range() - remove a range of GPIOs fro a pin controller
* @pctldev: pin controller device to remove the range from
......
......@@ -106,6 +106,19 @@ static struct pinctrl_dev *find_pinctrl_by_of_node(struct device_node *np)
return NULL;
}
struct pinctrl_dev *of_pinctrl_add_gpio_range(struct device_node *np,
struct pinctrl_gpio_range *range)
{
struct pinctrl_dev *pctldev;
pctldev = find_pinctrl_by_of_node(np);
if (!pctldev)
return NULL;
pinctrl_add_gpio_range(pctldev, range);
return pctldev;
}
static int dt_to_map_one_config(struct pinctrl *p, const char *statename,
struct device_node *np_config)
{
......
......@@ -5,6 +5,7 @@
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/of.h>
#include <linux/pinctrl/pinctrl.h>
#ifdef CONFIG_GPIOLIB
......@@ -47,6 +48,21 @@ struct seq_file;
struct module;
struct device_node;
#ifdef CONFIG_PINCTRL
/**
* struct gpio_pin_range - pin range controlled by a gpio chip
* @head: list for maintaining set of pin ranges, used internally
* @pctldev: pinctrl device which handles corresponding pins
* @range: actual range of pins controlled by a gpio controller
*/
struct gpio_pin_range {
struct list_head node;
struct pinctrl_dev *pctldev;
struct pinctrl_gpio_range range;
};
#endif
/**
* struct gpio_chip - abstract a GPIO controller
* @label: for diagnostics
......@@ -134,6 +150,15 @@ struct gpio_chip {
int (*of_xlate)(struct gpio_chip *gc,
const struct of_phandle_args *gpiospec, u32 *flags);
#endif
#ifdef CONFIG_PINCTRL
/*
* If CONFIG_PINCTRL is enabled, then gpio controllers can optionally
* describe the actual pin range which they serve in an SoC. This
* information would be used by pinctrl subsystem to configure
* corresponding pins for gpio usage.
*/
struct list_head pin_ranges;
#endif
};
extern const char *gpiochip_is_requested(struct gpio_chip *chip,
......
......@@ -231,6 +231,9 @@ static inline int irq_to_gpio(unsigned irq)
return -EINVAL;
}
void gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
unsigned int pin_base, unsigned int npins);
void gpiochip_remove_pin_ranges(struct gpio_chip *chip);
#endif
#endif /* __LINUX_GPIO_H */
......@@ -136,6 +136,23 @@ extern void pinctrl_add_gpio_ranges(struct pinctrl_dev *pctldev,
unsigned nranges);
extern void pinctrl_remove_gpio_range(struct pinctrl_dev *pctldev,
struct pinctrl_gpio_range *range);
extern struct pinctrl_dev *find_pinctrl_and_add_gpio_range(const char *devname,
struct pinctrl_gpio_range *range);
#ifdef CONFIG_OF
extern struct pinctrl_dev *of_pinctrl_add_gpio_range(struct device_node *np,
struct pinctrl_gpio_range *range);
#else
static inline
struct pinctrl_dev *of_pinctrl_add_gpio_range(struct device_node *np,
struct pinctrl_gpio_range *range)
{
return NULL;
}
#endif /* CONFIG_OF */
extern const char *pinctrl_dev_get_name(struct pinctrl_dev *pctldev);
extern void *pinctrl_dev_get_drvdata(struct pinctrl_dev *pctldev);
#else
......
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