Re: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
From: Boris BREZILLON
Date: Thu Mar 13 2014 - 02:27:55 EST
Le 13/03/2014 07:00, Yang, Wenyou a écrit :
Hi JC,
-----Original Message-----
From: Jean-Christophe PLAGNIOL-VILLARD [mailto:plagnioj@xxxxxxxxxxxx]
Sent: Tuesday, March 11, 2014 7:14 PM
To: Yang, Wenyou
Cc: Jean-Christophe PLAGNIOL-VILLARD; mark.rutland@xxxxxxx;
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Subject: Re: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
On Mar 11, 2014, at 2:54 PM, Yang, Wenyou <Wenyou.Yang@xxxxxxxxx> wrote:
-----Original Message-----
From: Jean-Christophe PLAGNIOL-VILLARD [mailto:plagnioj@xxxxxxxxxxxx]
Sent: Tuesday, March 11, 2014 12:16 PM
To: Yang, Wenyou
Cc: Jean-Christophe PLAGNIOL-VILLARD; mark.rutland@xxxxxxx;
devicetree@xxxxxxxxxxxxxxx; pawel.moll@xxxxxxx;
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Subject: Re: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
On Mar 11, 2014, at 9:28 AM, Yang, Wenyou <Wenyou.Yang@xxxxxxxxx>
wrote:
Hi JC,
-----Original Message-----
From: Yang, Wenyou
Sent: Wednesday, March 05, 2014 1:32 PM
To: Jean-Christophe PLAGNIOL-VILLARD
Cc: linus.walleij@xxxxxxxxxx; b.brezillon@xxxxxxxxxxx; <linux-arm-
kernel@xxxxxxxxxxxxxxxxxxx> mailing list; Linux Kernel list;
devicetree@xxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx; pawel.moll@xxxxxxx;
mark.rutland@xxxxxxx; ijc+devicetree@xxxxxxxxxxxxxx;
galak@xxxxxxxxxxxxxx
Subject: RE: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
Hi JC,
-----Original Message-----
From: Jean-Christophe PLAGNIOL-VILLARD
[mailto:plagnioj@xxxxxxxxxxxx]
Sent: Wednesday, March 05, 2014 12:58 PM
To: Yang, Wenyou
Cc: Jean-Christophe PLAGNIOL-VILLARD; linus.walleij@xxxxxxxxxx;
b.brezillon@xxxxxxxxxxx; <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>
mailing list; Linux Kernel list; devicetree@xxxxxxxxxxxxxxx;
robh+dt@xxxxxxxxxx; pawel.moll@xxxxxxx; mark.rutland@xxxxxxx;
ijc+devicetree@xxxxxxxxxxxxxx; galak@xxxxxxxxxxxxxx
Subject: Re: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
On Mar 5, 2014, at 9:53 AM, Wenyou Yang <wenyou.yang@xxxxxxxxx>
wrote:
In order to support the pinctrl sleep state.
As I said before NACK
this is not the job of the pinctrl to describe gpio output or
input state
But according to what said in the section "GPIO mode pitfalls" of
Documentation/pinctrl.txt.
It should be handle by the pinctrl.
If not, to deal with the sleep state will be very complicated.
Muxing the pins for FUNCTION to enable peripheral, then twist them
over to GPIO mode and use gpio_direction_output() to drive it HIGH
or LOW during sleep.
--->8 ------------
The solution is to not think that what the datasheet calls "GPIO
mode"
has to be handled by the <linux/gpio.h> interface. Instead view
this as a certain pin config setting. Look in e.g.
<linux/pinctrl/pinconf- generic.h> and you find this in the
documentation:
PIN_CONFIG_OUTPUT: this will configure the pin in output, use
argument
1 to indicate high level, argument 0 to indicate low level.
So it is perfectly possible to push a pin into "GPIO mode" and
drive the line low as part of the usual pin control map.
---<8 ------------
Do you have any feedback?
Here the issue is that you do drive the gpio and use as a gpio
which means you request it as a GPIO so after you can not reswitch it
to alternative function and the gpio is already requested as
alternative function
So basically you mess-up with the gpio API and pinctrl API by
bypassing both
But I don't agree with you.
As I known, in mainline the other SoC vendors provide such function,
configure the gpio mode with output config by pinctrl.
For example, ST. nomadisk.
You can see it in the function: nmk_pin_config_set() of the file,
pinctrl-nomadik.c.
It provides GPIO mode and OUTPUT config.
This is a good solution, as what said in Documentation/pinctrl.txt,
it is perfectly possible to push a pin into "GPIO mode" and drive the
line low as part of the usual pin control map.
This is simple if we use gpio mode as pinctrl tomorrow we will see gpio
configuration in pinctrl such as chip reset, default led state etc...
The pinctrl is not here to control a *GPIO* but to describe the
configuration of pin.
What you said is the usual use case.
But, in the Power Management scenario, there are the following requirements to meet:
When running time, the pins are configured as the PERIPH functions by the pinctrl default state as usaul.
When suspending to memory, the pins are configured as GPIO output low, output high or input by the pinctrl sleep state.
When resuming from suspended, the pins are configured back as the PERIPH functions.
I just found the same implementation by Boris which is better.
http://lists.infradead.org/pipermail/linux-arm-kernel/2013-August/194975.html
Boris, Could you have something to say?
Yes.
I still think the pinconf OUTPUT state is useful in some cases, and the
one you described is obviously one of these (I needed it for a different
reason : https://lkml.org/lkml/2013/8/28/203 which appeared to be a wrong
one).
But I'm not the pinctrl subsystem or the at91 pinctrl driver maintainer...
Linus, do you have an opinion on this feature ?
Signed-off-by: Wenyou Yang <wenyou.yang@xxxxxxxxx>
---
Hi Linus,
The patch is based on branch: for-next
git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctr
l
Best Regards,
Wenyou Yang
drivers/pinctrl/pinctrl-at91.c | 31
+++++++++++++++++++++++++++++++
include/dt-bindings/pinctrl/at91.h | 2 ++
2 files changed, 33 insertions(+)
diff --git a/drivers/pinctrl/pinctrl-at91.c
b/drivers/pinctrl/pinctrl-at91.c index 5d24aae..fc51e59 100644
--- a/drivers/pinctrl/pinctrl-at91.c
+++ b/drivers/pinctrl/pinctrl-at91.c
@@ -62,6 +62,8 @@ static int gpio_banks;
#define DEGLITCH (1 << 2)
#define PULL_DOWN (1 << 3)
#define DIS_SCHMIT (1 << 4)
+#define GPIO_OUTPUT_HIGH (1 << 5)
+#define GPIO_OUTPUT_LOW (1 << 6)
#define DEBOUNCE (1 << 16)
#define DEBOUNCE_VAL_SHIFT 17
#define DEBOUNCE_VAL (0x3fff << DEBOUNCE_VAL_SHIFT)
@@ -152,12 +154,15 @@ struct at91_pinctrl_mux_ops {
void (*set_pulldown)(void __iomem *pio, unsigned mask, bool
is_on);
bool (*get_schmitt_trig)(void __iomem *pio, unsigned pin);
void (*disable_schmitt_trig)(void __iomem *pio, unsigned
mask);
+ bool (*get_gpio_output)(void __iomem *pio, unsigned mask);
+ void (*set_gpio_output)(void __iomem *pio, unsigned mask,
bool
+is_high);
/* irq */
int (*irq_type)(struct irq_data *d, unsigned type); };
static int gpio_irq_type(struct irq_data *d, unsigned type);
static int alt_gpio_irq_type(struct irq_data *d, unsigned type);
+static void at91_mux_gpio_enable(void __iomem *pio, unsigned
+mask, bool input);
struct at91_pinctrl {
struct device *dev;
@@ -472,6 +477,20 @@ static bool
at91_mux_pio3_get_schmitt_trig(void
__iomem *pio, unsigned pin)
return (__raw_readl(pio + PIO_SCHMITT) >> pin) & 0x1; }
+static bool at91_mux_pio3_get_gpio_output(void __iomem *pio,
+unsigned
+pin) {
+ return (__raw_readl(pio + PIO_ODSR) >> pin) & 0x1; }
+
+static void at91_mux_pio3_set_gpio_output(void __iomem *pio,
+ unsigned mask,
+ bool is_high)
+{
+ at91_mux_gpio_enable(pio, mask, 0);
+ writel_relaxed(mask, pio + (is_high ? PIO_SODR : PIO_CODR)); }
+
+
static struct at91_pinctrl_mux_ops at91rm9200_ops = {
.get_periph = at91_mux_get_periph,
.mux_A_periph = at91_mux_set_A_periph,
@@ -495,6 +514,8 @@ static struct at91_pinctrl_mux_ops
at91sam9x5_ops
= {
.set_pulldown = at91_mux_pio3_set_pulldown,
.get_schmitt_trig = at91_mux_pio3_get_schmitt_trig,
.disable_schmitt_trig = at91_mux_pio3_disable_schmitt_trig,
+ .get_gpio_output = at91_mux_pio3_get_gpio_output,
+ .set_gpio_output = at91_mux_pio3_set_gpio_output,
.irq_type = alt_gpio_irq_type,
};
@@ -741,6 +762,10 @@ static int at91_pinconf_get(struct
pinctrl_dev
*pctldev,
*config |= PULL_DOWN;
if (info->ops->get_schmitt_trig &&
info->ops->get_schmitt_trig(pio,
pin))
*config |= DIS_SCHMIT;
+ if (info->ops->get_gpio_output) {
+ *config |= info->ops->get_gpio_output(pio, pin) ?
+ GPIO_OUTPUT_HIGH : GPIO_OUTPUT_LOW;
+ }
return 0;
}
@@ -778,6 +803,12 @@ static int at91_pinconf_set(struct
pinctrl_dev
*pctldev,
info->ops->set_pulldown(pio, mask, config &
PULL_DOWN);
if (info->ops->disable_schmitt_trig && config &
DIS_SCHMIT)
info->ops->disable_schmitt_trig(pio, mask);
+ if (info->ops->set_gpio_output) {
+ if (config & GPIO_OUTPUT_HIGH)
+ info->ops->set_gpio_output(pio, mask, 1);
+ if (config & GPIO_OUTPUT_LOW)
+ info->ops->set_gpio_output(pio, mask, 0);
+ };
} /* for each config */
diff --git a/include/dt-bindings/pinctrl/at91.h
b/include/dt-bindings/pinctrl/at91.h
index 0fee6ff..e799268 100644
--- a/include/dt-bindings/pinctrl/at91.h
+++ b/include/dt-bindings/pinctrl/at91.h
@@ -15,6 +15,8 @@
#define AT91_PINCTRL_DEGLITCH (1 << 2)
#define AT91_PINCTRL_PULL_DOWN (1 << 3)
#define AT91_PINCTRL_DIS_SCHMIT (1 << 4)
+#define AT91_PINCTRL_OUTPUT_HIGH (1 << 5)
+#define AT91_PINCTRL_OUTPUT_LOW (1 << 6)
#define AT91_PINCTRL_DEBOUNCE (1 << 16)
#define AT91_PINCTRL_DEBOUNCE_VAL(x) (x << 17)
--
1.7.9.5
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Bes Regards,
Wenyou Yang
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