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Subject[PATCH] pinctrl: at91-pio4: add support for drive-strength property
Date
Add support for the drive-strength property. Usually its value is
expressed in mA. Since the numeric value depends on VDDIOP voltage,
the controller uses low, medium and high to define the drive-strengh.

The PIO controller accepts two values for the low drive: 0 or 1. Most
of the time, we don't care about the drive strength, there is no need
to change it, so 0 is considered as the default value. The low-drive
value won't be advertised through pinconf-pins file excepted if it
has been set explicitly in the device tree ie if its value is
different from 0.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
---
.../bindings/pinctrl/atmel,at91-pio4-pinctrl.txt | 5 ++--
drivers/pinctrl/pinctrl-at91-pio4.c | 33 ++++++++++++++++++++++
include/dt-bindings/pinctrl/at91.h | 4 +++
3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/pinctrl/atmel,at91-pio4-pinctrl.txt b/Documentation/devicetree/bindings/pinctrl/atmel,at91-pio4-pinctrl.txt
index 61ac75706cc9..183064bc4bda 100644
--- a/Documentation/devicetree/bindings/pinctrl/atmel,at91-pio4-pinctrl.txt
+++ b/Documentation/devicetree/bindings/pinctrl/atmel,at91-pio4-pinctrl.txt
@@ -34,8 +34,8 @@ right representation of the pin.

Optional properties:
- GENERIC_PINCONFIG: generic pinconfig options to use, bias-disable,
-bias-pull-down, bias-pull-up, drive-open-drain, input-schmitt-enable,
-input-debounce, output-low, output-high.
+bias-pull-down, bias-pull-up, drive-open-drain, drive-strength,
+input-schmitt-enable, input-debounce, output-low, output-high.

Example:

@@ -66,6 +66,7 @@ Example:
pinmux = <PIN_PB0>,
<PIN_PB5>;
bias-pull-up;
+ drive-strength = <ATMEL_PIO_DRVSTR_LO>;
};

pinctrl_sdmmc1_default: sdmmc1_default {
diff --git a/drivers/pinctrl/pinctrl-at91-pio4.c b/drivers/pinctrl/pinctrl-at91-pio4.c
index 4b57a13758a4..857c0a41a905 100644
--- a/drivers/pinctrl/pinctrl-at91-pio4.c
+++ b/drivers/pinctrl/pinctrl-at91-pio4.c
@@ -14,6 +14,7 @@
* GNU General Public License for more details.
*/

+#include <dt-bindings/pinctrl/at91.h>
#include <linux/clk.h>
#include <linux/gpio/driver.h>
/* FIXME: needed for gpio_to_irq(), get rid of this */
@@ -49,6 +50,8 @@
#define ATMEL_PIO_IFSCEN_MASK BIT(13)
#define ATMEL_PIO_OPD_MASK BIT(14)
#define ATMEL_PIO_SCHMITT_MASK BIT(15)
+#define ATMEL_PIO_DRVSTR_MASK GENMASK(17, 16)
+#define ATMEL_PIO_DRVSTR_OFFSET 16
#define ATMEL_PIO_CFGR_EVTSEL_MASK GENMASK(26, 24)
#define ATMEL_PIO_CFGR_EVTSEL_FALLING (0 << 24)
#define ATMEL_PIO_CFGR_EVTSEL_RISING (1 << 24)
@@ -685,6 +688,11 @@ static int atmel_conf_pin_config_group_get(struct pinctrl_dev *pctldev,
return -EINVAL;
arg = 1;
break;
+ case PIN_CONFIG_DRIVE_STRENGTH:
+ if (!(res & ATMEL_PIO_DRVSTR_MASK))
+ return -EINVAL;
+ arg = (res & ATMEL_PIO_DRVSTR_MASK) >> ATMEL_PIO_DRVSTR_OFFSET;
+ break;
case PIN_CONFIG_INPUT_SCHMITT_ENABLE:
if (!(res & ATMEL_PIO_SCHMITT_MASK))
return -EINVAL;
@@ -737,6 +745,18 @@ static int atmel_conf_pin_config_group_set(struct pinctrl_dev *pctldev,
else
conf |= ATMEL_PIO_OPD_MASK;
break;
+ case PIN_CONFIG_DRIVE_STRENGTH:
+ switch (arg) {
+ case ATMEL_PIO_DRVSTR_LO:
+ case ATMEL_PIO_DRVSTR_ME:
+ case ATMEL_PIO_DRVSTR_HI:
+ conf &= (~ATMEL_PIO_DRVSTR_MASK);
+ conf |= arg << ATMEL_PIO_DRVSTR_OFFSET;
+ break;
+ default:
+ dev_warn(pctldev->dev, "drive strength not updated (incorrect value)\n");
+ }
+ break;
case PIN_CONFIG_INPUT_SCHMITT_ENABLE:
if (arg == 0)
conf |= ATMEL_PIO_SCHMITT_MASK;
@@ -814,6 +834,19 @@ static void atmel_conf_pin_config_dbg_show(struct pinctrl_dev *pctldev,
seq_printf(s, "%s ", "open-drain");
if (conf & ATMEL_PIO_SCHMITT_MASK)
seq_printf(s, "%s ", "schmitt");
+ if (conf & ATMEL_PIO_DRVSTR_MASK) {
+ switch ((conf & ATMEL_PIO_DRVSTR_MASK) >> ATMEL_PIO_DRVSTR_OFFSET) {
+ case ATMEL_PIO_DRVSTR_LO:
+ seq_printf(s, "%s ", "low-drive");
+ break;
+ case ATMEL_PIO_DRVSTR_ME:
+ seq_printf(s, "%s ", "medium-drive");
+ break;
+ case ATMEL_PIO_DRVSTR_HI:
+ seq_printf(s, "%s ", "high-drive");
+ break;
+ }
+ }
}

static const struct pinconf_ops atmel_confops = {
diff --git a/include/dt-bindings/pinctrl/at91.h b/include/dt-bindings/pinctrl/at91.h
index 2732d6c0fb39..eb81867eac77 100644
--- a/include/dt-bindings/pinctrl/at91.h
+++ b/include/dt-bindings/pinctrl/at91.h
@@ -39,4 +39,8 @@
#define AT91_PERIPH_C 3
#define AT91_PERIPH_D 4

+#define ATMEL_PIO_DRVSTR_LO 1
+#define ATMEL_PIO_DRVSTR_ME 2
+#define ATMEL_PIO_DRVSTR_HI 3
+
#endif /* __DT_BINDINGS_AT91_PINCTRL_H__ */
--
2.12.2
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