tegra: harmony: wifi: add board support for WiFi

The SDIO WiFi module requires power from external PMU and 1.2V regulator.
The module gets powered on if - (1) all power sources are enabled, and
(2) power (down) and reset (down) pins are enabled as per spec.

To enable mmc/SDIO driver to detect the WiFi hardware, the WiFi chip has
to be powered-up before mmc driver does probing. So, steps should be as
following: (1) required regulators are on, (2) power/reset of WiFi are
enabled, (3) mmc does probing. Later time, when WiFi driver module is
loaded and registers with SDIO, the SDIO driver knows which H/W the driver
has to be associated with.

Bug: 908534
Change-Id: I6510bced5fa9b8b3314c00180f2694903b23145c
Reviewed-on: http://git-master/r/#change,47808,patchset=2
Signed-off-by: Preetham Chandru <pchandru@nvidia.com>
Reviewed-on: http://git-master/r/67121
Reviewed-by: Mursalin Akon <makon@nvidia.com>
Reviewed-by: Allen Martin <amartin@nvidia.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/board-harmony.c b/arch/arm/mach-tegra/board-harmony.c
index ad9c43b0ae9a..9fb1c8fbce0c 100644
--- a/arch/arm/mach-tegra/board-harmony.c
+++ b/arch/arm/mach-tegra/board-harmony.c
@@ -29,6 +29,7 @@
 #include <linux/i2c.h>
 #include <linux/i2c-tegra.h>
 #include <linux/memblock.h>
+#include <linux/delay.h>
 
 #include <sound/wm8903.h>
 
@@ -377,6 +378,41 @@ static struct tegra_sdhci_platform_data sdhci_pdata4 = {
 	.is_8bit	= 1,
 };
 
+static int __init harmony_wifi_init(void)
+{
+        int gpio_pwr, gpio_rst;
+
+	if (!machine_is_harmony())
+		return 0;
+
+        /* WLAN - Power up (low) and Reset (low) */
+        gpio_pwr = gpio_request(TEGRA_GPIO_WLAN_PWR_LOW, "wlan_pwr");
+        gpio_rst = gpio_request(TEGRA_GPIO_WLAN_RST_LOW, "wlan_rst");
+        if (gpio_pwr < 0 || gpio_rst < 0)
+                pr_warning("Unable to get gpio for WLAN Power and Reset\n");
+        else {
+
+		tegra_gpio_enable(TEGRA_GPIO_WLAN_PWR_LOW);
+		tegra_gpio_enable(TEGRA_GPIO_WLAN_RST_LOW);
+                /* toggle in this order as per spec */
+                gpio_direction_output(TEGRA_GPIO_WLAN_PWR_LOW, 0);
+                gpio_direction_output(TEGRA_GPIO_WLAN_RST_LOW, 0);
+		udelay(5);
+                gpio_direction_output(TEGRA_GPIO_WLAN_PWR_LOW, 1);
+                gpio_direction_output(TEGRA_GPIO_WLAN_RST_LOW, 1);
+        }
+
+	return 0;
+}
+
+/*
+ * subsys_initcall_sync is good synch point to call harmony_wifi_init
+ * This makes sure that the required regulators (LDO3
+ * supply of external PMU and 1.2V regulator) are properly enabled,
+ * and mmc driver has not yet probed for a device on SDIO bus.
+ */
+subsys_initcall_sync(harmony_wifi_init);
+
 static void __init tegra_harmony_init(void)
 {
 	tegra_clk_init_from_table(harmony_clk_init_table);