[PATCH v2 07/12] ARM: imx6q: add config-on-boot gpios

On Tue, May 22, 2012 at 11:17:12AM +0800, Shawn Guo wrote:

Apart from my comments below, we really need to know Rob and Grant's
opinion on this.

Exactly. I cced them to draw their attention.

On Mon, May 21, 2012 at 05:23:52PM +0800, Richard Zhao wrote:

quoted

Sometimes, boards have gpios that don't own by any driver or owner
by a generic driver that don't like hacks. Such gpios is normally
output and need setup once on boot. So I introduce the config-on-boot
gpios.

Signed-off-by: Richard Zhao <redacted>
Cc: Shawn Guo <redacted>
Cc: Rob Herring <redacted>
Cc: Grant Likely <redacted>
---
 arch/arm/boot/dts/imx6q-sabrelite.dts |    7 ++++++
 arch/arm/mach-imx/mach-imx6q.c        |   35 +++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/arch/arm/boot/dts/imx6q-sabrelite.dts b/arch/arm/boot/dts/imx6q-sabrelite.dts
index e0ec929..1dd2261 100644
--- a/arch/arm/boot/dts/imx6q-sabrelite.dts
+++ b/arch/arm/boot/dts/imx6q-sabrelite.dts

@@ -17,6 +17,13 @@
 	model = "Freescale i.MX6 Quad SABRE Lite Board";
 	compatible = "fsl,imx6q-sabrelite", "fsl,imx6q";
 
+	config-on-boot {
+		output-gpios = <
+				&gpio3 22 0>;	/* vbus reset */
+		output-gpio-values = <
+				1>;		/* vbus reset */
+	};
+

So it looks like something not specific to imx board but generic to
other boards.  If so, we may need to come up with a generic binding
document for this.

Yes.

Is this only used to configure output pin?  Will there be any pin that
needs to be configured as input but not owned by any driver?  Hopefully
not.

I didn't see the case yet. Input pin normally has a corresponding driver. 

quoted

 	memory {
 		reg = <0x10000000 0x40000000>;
 	};

diff --git a/arch/arm/mach-imx/mach-imx6q.c b/arch/arm/mach-imx/mach-imx6q.c
index b47e98b..577cf19 100644
--- a/arch/arm/mach-imx/mach-imx6q.c
+++ b/arch/arm/mach-imx/mach-imx6q.c

@@ -19,6 +19,7 @@
 #include <linux/irqdomain.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_gpio.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/pinctrl/machine.h>

@@ -113,6 +114,38 @@ static void __init imx6q_sabrelite_init(void)
 	imx6q_sabrelite_cko1_setup();
 }
 
+static void __init imx6q_config_on_boot(void)

Do you intend to make this function non-gpio-config only.  Otherwise,
we may need to have "gpio" in the function name, as well as the
"config-on-boot" node name.

config-on-boot is not specific for gpio, but may be for others. For
example, regulators. For now, it only has output gpios.

Also, if we define the binding as generic one, we may need to find a
common place to implement the function.

Yes. But it's better be called at machine init after populate devices.

quoted

+{
+	struct device_node *np;
+	struct property *pp;
+	int cnt, len, i;
+	int gpio;
+
+	np = of_find_node_by_path("/config-on-boot");
+	if (!np)
+		return;
+	cnt = of_gpio_named_count(np, "output-gpios");
+	pp = of_find_property(np, "output-gpio-values", &len);
+	if (!pp || cnt != len / sizeof(u32)) {
+		pr_err("Invalid config-on-boot gpios!\n");
+		of_node_put(np);
+		return;
+	}
+	for (i = 0; i < cnt; i++) {
+		gpio = of_get_named_gpio(np, "output-gpios", i);
+		if (gpio_is_valid(gpio))
+			gpio_request_one(gpio, GPIOF_OUT_INIT_HIGH,
+					"config-on-boot");

So all the gpios will use the same name.

Yes.

And doesn't the reset generally need a pulse or edge signal, e.g. pull
down for a msec and pull up?

strict reset is too complicated for config-on-boot. It may need delay
some time case by case. I don't have the case yet. But someone may
add it if it really needed, probably with addon properties.

Thanks
Richard

Regards,
Shawn

quoted

+	}
+
+	of_node_put(np);
+}
+
+static void __init imx6q_post_populate(void)
+{
+	imx6q_config_on_boot();
+}
+
 static void __init imx6q_init_machine(void)
 {
 	/*

@@ -126,6 +159,8 @@ static void __init imx6q_init_machine(void)
 
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
 
+	imx6q_post_populate();
+
 	imx6q_pm_init();
 }
 

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1.7.5.4