diff mbox series

[net-next,v2,1/1] net: stmmac: use GPIO descriptors in stmmac_mdio_reset

Message ID 20190612193115.6751-2-martin.blumenstingl@googlemail.com (mailing list archive)
State New, archived
Headers show
Series stmmac: honor the GPIO flags for the PHY reset GPIO | expand

Commit Message

Martin Blumenstingl June 12, 2019, 7:31 p.m. UTC 
Switch stmmac_mdio_reset to use GPIO descriptors. GPIO core handles the
"snps,reset-gpio" for GPIO descriptors so we don't need to take care of
it inside the driver anymore.

The advantage of this is that we now preserve the GPIO flags which are
passed via devicetree. This is required on some newer Amlogic boards
which use an Open Drain pin for the reset GPIO. This pin can only output
a LOW signal or switch to input mode but it cannot output a HIGH signal.
There are already devicetree bindings for these special cases and GPIO
core already takes care of them but only if we use GPIO descriptors
instead of GPIO numbers.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 .../net/ethernet/stmicro/stmmac/stmmac_mdio.c | 27 +++++++++----------
 include/linux/stmmac.h                        |  2 +-
 2 files changed, 14 insertions(+), 15 deletions(-)

Comments

Andrew Lunn June 12, 2019, 9:09 p.m. UTC | #1 
On Wed, Jun 12, 2019 at 09:31:15PM +0200, Martin Blumenstingl wrote:
> Switch stmmac_mdio_reset to use GPIO descriptors. GPIO core handles the
> "snps,reset-gpio" for GPIO descriptors so we don't need to take care of
> it inside the driver anymore.
> 
> The advantage of this is that we now preserve the GPIO flags which are
> passed via devicetree. This is required on some newer Amlogic boards
> which use an Open Drain pin for the reset GPIO. This pin can only output
> a LOW signal or switch to input mode but it cannot output a HIGH signal.
> There are already devicetree bindings for these special cases and GPIO
> core already takes care of them but only if we use GPIO descriptors
> instead of GPIO numbers.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew
David Miller June 15, 2019, 2:08 a.m. UTC | #2 
From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date: Wed, 12 Jun 2019 21:31:15 +0200

> Switch stmmac_mdio_reset to use GPIO descriptors. GPIO core handles the
> "snps,reset-gpio" for GPIO descriptors so we don't need to take care of
> it inside the driver anymore.
> 
> The advantage of this is that we now preserve the GPIO flags which are
> passed via devicetree. This is required on some newer Amlogic boards
> which use an Open Drain pin for the reset GPIO. This pin can only output
> a LOW signal or switch to input mode but it cannot output a HIGH signal.
> There are already devicetree bindings for these special cases and GPIO
> core already takes care of them but only if we use GPIO descriptors
> instead of GPIO numbers.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Applied.
Linus Walleij June 15, 2019, 9:07 a.m. UTC | #3 
Hi Martin!

Thanks for fixing this up!

A hint for a follow-up:

On Wed, Jun 12, 2019 at 9:31 PM Martin Blumenstingl
<martin.blumenstingl@googlemail.com> wrote:

> diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
> index 4335bd771ce5..816edb545592 100644
> --- a/include/linux/stmmac.h
> +++ b/include/linux/stmmac.h
> @@ -97,7 +97,7 @@ struct stmmac_mdio_bus_data {
>         int *irqs;
>         int probed_phy_irq;
>  #ifdef CONFIG_OF
> -       int reset_gpio, active_low;
> +       int reset_gpio;

Nothing in the kernel seems to be using this reset_gpio either.

I think it can be deleted with associated code, any new users
should use machine descriptors if they insist on board files.

Yours,
Linus Walleij
Martin Blumenstingl June 15, 2019, 9:11 a.m. UTC | #4 
Hi Linus,

On Sat, Jun 15, 2019 at 11:08 AM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> Hi Martin!
>
> Thanks for fixing this up!
you're welcome
I think I finally understand why you want to switch everything over to
GPIO descriptors

> A hint for a follow-up:
>
> On Wed, Jun 12, 2019 at 9:31 PM Martin Blumenstingl
> <martin.blumenstingl@googlemail.com> wrote:
>
> > diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
> > index 4335bd771ce5..816edb545592 100644
> > --- a/include/linux/stmmac.h
> > +++ b/include/linux/stmmac.h
> > @@ -97,7 +97,7 @@ struct stmmac_mdio_bus_data {
> >         int *irqs;
> >         int probed_phy_irq;
> >  #ifdef CONFIG_OF
> > -       int reset_gpio, active_low;
> > +       int reset_gpio;
>
> Nothing in the kernel seems to be using this reset_gpio either.
>
> I think it can be deleted with associated code, any new users
> should use machine descriptors if they insist on board files.
good catch, thank you - I'll put that in my cleanup series that I want
to send anyways


Martin
Linus Walleij June 15, 2019, 9:34 a.m. UTC | #5 
On Sat, Jun 15, 2019 at 11:11 AM Martin Blumenstingl
<martin.blumenstingl@googlemail.com> wrote:

> I think I finally understand why you want to switch everything over to
> GPIO descriptors

A bit after-the-fact reasoning, but after I was made aware of an interesting
lecture by John Ousterhout I feel the best description of the descriptor
refactoring is the idea to make the GPIO API narrow and deep, make
it simple for consumers (hence <linux/gpio/consumer.h>) and handle
as much special cases (polarity inversion, open drain...) as possible
behind the scenes.

Yours,
Linus Walleij
diff mbox series

Patch

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index 093a223fe408..f1c39dd048e7 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -20,11 +20,11 @@ 
   Maintainer: Giuseppe Cavallaro <peppe.cavallaro@st.com>
 *******************************************************************************/
 
+#include <linux/gpio/consumer.h>
 #include <linux/io.h>
 #include <linux/iopoll.h>
 #include <linux/mii.h>
 #include <linux/of.h>
-#include <linux/of_gpio.h>
 #include <linux/of_mdio.h>
 #include <linux/phy.h>
 #include <linux/slab.h>
@@ -251,37 +251,36 @@  int stmmac_mdio_reset(struct mii_bus *bus)
 
 #ifdef CONFIG_OF
 	if (priv->device->of_node) {
+		struct gpio_desc *reset_gpio;
+
 		if (data->reset_gpio < 0) {
 			struct device_node *np = priv->device->of_node;
 
 			if (!np)
 				return 0;
 
-			data->reset_gpio = of_get_named_gpio(np,
-						"snps,reset-gpio", 0);
-			if (data->reset_gpio < 0)
-				return 0;
+			reset_gpio = devm_gpiod_get_optional(priv->device,
+							     "snps,reset",
+							     GPIOD_OUT_LOW);
+			if (IS_ERR(reset_gpio))
+				return PTR_ERR(reset_gpio);
 
-			data->active_low = of_property_read_bool(np,
-						"snps,reset-active-low");
 			of_property_read_u32_array(np,
 				"snps,reset-delays-us", data->delays, 3);
+		} else {
+			reset_gpio = gpio_to_desc(data->reset_gpio);
 
-			if (devm_gpio_request(priv->device, data->reset_gpio,
-					      "mdio-reset"))
-				return 0;
+			gpiod_direction_output(reset_gpio, 0);
 		}
 
-		gpio_direction_output(data->reset_gpio,
-				      data->active_low ? 1 : 0);
 		if (data->delays[0])
 			msleep(DIV_ROUND_UP(data->delays[0], 1000));
 
-		gpio_set_value(data->reset_gpio, data->active_low ? 0 : 1);
+		gpiod_set_value_cansleep(reset_gpio, 1);
 		if (data->delays[1])
 			msleep(DIV_ROUND_UP(data->delays[1], 1000));
 
-		gpio_set_value(data->reset_gpio, data->active_low ? 1 : 0);
+		gpiod_set_value_cansleep(reset_gpio, 0);
 		if (data->delays[2])
 			msleep(DIV_ROUND_UP(data->delays[2], 1000));
 	}
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 4335bd771ce5..816edb545592 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -97,7 +97,7 @@  struct stmmac_mdio_bus_data {
 	int *irqs;
 	int probed_phy_irq;
 #ifdef CONFIG_OF
-	int reset_gpio, active_low;
+	int reset_gpio;
 	u32 delays[3];
 #endif
 };