Toggling gpio pins while powering down

[Jasbir Matharu]

I'm trying to determine the correct way of toggling gpio pins when the
soc is powering down to enter low power mode. My current crude
implementation is perform these within a pm_power_off function however
this is currently done within the board file by checking for a
compatible board type (ugly). The alternative would be create a driver
and implement the pm_power_off function within. However given there
could many drivers implementing a pm_power_off functions there's no
guarantee mine will be called? Another requirement is that the gpio
need to be set in the correct order.

diff --git a/arch/arm/boot/dts/imx6q-udoo.dts b/arch/arm/boot/dts/imx6q-udoo.dts
index 0ce92cd..e5e2af9 100644
--- a/arch/arm/boot/dts/imx6q-udoo.dts
+++ b/arch/arm/boot/dts/imx6q-udoo.dts
@@ -62,6 +62,13 @@
  compatible = "fsl,mxc_v4l2_output";
  status = "okay";
  };
+
+ poweroff {
+ compatible = "udoo,poweroff";
+ sam3x_rst_gpio = <&gpio1 0 0>;
+ pwr_5v_gpio = <&gpio2 4 0>;
+ };
+
 };

 &hdmi_audio {
diff --git a/arch/arm/mach-imx/mach-imx6q.c b/arch/arm/mach-imx/mach-imx6q.c
index f24c231..3fea3fd 100644
--- a/arch/arm/mach-imx/mach-imx6q.c
+++ b/arch/arm/mach-imx/mach-imx6q.c
@@ -34,6 +34,7 @@
 #include <linux/mfd/syscon.h>
 #include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
 #include <linux/of_net.h>
+#include <linux/delay.h>
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
 #include <asm/system_misc.h>
@@ -336,6 +337,55 @@ static const struct of_dev_auxdata
imx6q_auxdata_lookup[] __initconst = {
  { /* sentinel */ }
 };

+#define SNVS_LPCR 0x04
+static void imx6q_poweroff(void)
+{
+ struct device_node *snvs_np, *pwr_off_np;
+ void __iomem *mx6_snvs_base;
+ u32 value;
+ int sam3x_rst_gpio,pwr_5v_gpio;
+
+ snvs_np = of_find_compatible_node(NULL, NULL, "fsl,sec-v4.0-mon-rtc-lp");
+ if (!snvs_np) {
+ pr_warn("failed to find sec-v4.0-mon-rtc-lp node\n");
+ return;
+ }
+
+ mx6_snvs_base = of_iomap(snvs_np, 0);
+ if (!mx6_snvs_base) {
+ pr_warn("failed to map sec-v4.0-mon-rtc-lp\n");
+ goto put_snvs_node;
+ }
+
+    value = readl(mx6_snvs_base + SNVS_LPCR);
+    /*set TOP and DP_EN bit*/
+    writel(value | 0x60, mx6_snvs_base + SNVS_LPCR);
+
+ if (of_machine_is_compatible("udoo,imx6q-udoo")) {
+ // Power down SAM3X and UDOO
+ pwr_off_np = of_find_compatible_node(NULL, NULL, "udoo,poweroff");
+ if (!pwr_off_np) {
+ pr_warn("failed to find udoo,poweroff node\n");
+ goto put_snvs_node;
+ }
+
+ sam3x_rst_gpio = of_get_named_gpio(pwr_off_np, "sam3x_rst_gpio", 0);
+ pwr_5v_gpio = of_get_named_gpio(pwr_off_np, "pwr_5v_gpio", 0);
+ if (gpio_is_valid(sam3x_rst_gpio) && gpio_is_valid(pwr_5v_gpio)) {
+ gpio_request_one(sam3x_rst_gpio, GPIOF_OUT_INIT_LOW,"sam3x_rst_gpio"),
+ msleep(5);
+ gpio_request_one(pwr_5v_gpio, GPIOF_OUT_INIT_HIGH,"pwr_5v_gpio");
+ } else {
+ pr_warn("failed to find sam3x_rst_gpio or pwr_5v_gpio property\n");
+ }
+
+ }
+
+ of_node_put(pwr_off_np);
+put_snvs_node:
+ of_node_put(snvs_np);
+}
+
 static void __init imx6q_init_machine(void)
 {
  struct device *parent;
@@ -353,6 +403,8 @@ static void __init imx6q_init_machine(void)
  imx6_pm_init();
  imx6q_csi_mux_init();
  imx6q_lvds_cabc_init();
+
+ pm_power_off = imx6q_poweroff;
 }