From 769780f8a13c785657f469f65041ea6945bfa721 Mon Sep 17 00:00:00 2001
From: Aniruddha Rao <anrao@nvidia.com>
Date: Mon, 27 Jul 2020 12:22:27 +0530
Subject: [PATCH] NVIDIA: SAUCE: mmc: tegra: use gpio for voltage switching on
 fpga

Use dt property "nvidia,voltage-switch-gpio" parsed from DT
to select voltage level and toggle it for switching voltage
from 3.3V to 1.8V to support SD3.0 cards on FPGA.

http://nvbugs/2836586
http://nvbugs/2849456
http://nvbugs/4333277

Signed-off-by: Aniruddha Rao <anrao@nvidia.com>
(cherry-picked from commit b99819f98ef04c50b4a050a9f49e7e3c223868b1 and
and edited by anrao to work in k5.9)
Signed-off-by: Prathamesh Shete <pshete@nvidia.com>
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Acked-by: Noah Wager <noah.wager@canonical.com>
Acked-by: Jacob Martin <jacob.martin@canonical.com>
Signed-off-by: Noah Wager <noah.wager@canonical.com>
---
 drivers/mmc/host/sdhci-tegra.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
index 15a817e40612..a13e7b2a5ad8 100644
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -26,6 +26,8 @@
 #include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
 
 #include <soc/tegra/common.h>
 #include <soc/tegra/fuse.h>
@@ -213,6 +215,7 @@ struct sdhci_tegra {
 	u32 stream_id;
 	bool skip_clk_rst;
 	struct tegra_prod *prod_list;
+	int volt_switch_gpio;
 };
 
 static u16 tegra_sdhci_readw(struct sdhci_host *host, int reg)
@@ -548,8 +551,20 @@ static int tegra_sdhci_set_padctrl(struct sdhci_host *host, int voltage,
 			sdhci_writel(host, reg,
 					SDHCI_TEGRA_SDMEM_COMP_PADCTRL);
 		}
-
 	} else {
+		/* Toggle power gpio for switching voltage on FPGA */
+		if (gpio_is_valid(tegra_host->volt_switch_gpio)) {
+			if (voltage == MMC_SIGNAL_VOLTAGE_330) {
+				gpio_set_value(tegra_host->volt_switch_gpio, 1);
+				dev_info(mmc_dev(host->mmc),
+					 "3.3V set by voltage switch gpio\n");
+			} else {
+				gpio_set_value(tegra_host->volt_switch_gpio, 0);
+				dev_info(mmc_dev(host->mmc),
+					 "1.8V set by voltage switch gpio\n");
+			}
+			return 0;
+		}
 		/* Dual Voltage PADS Voltage selection */
 		if (!tegra_host->pad_control_available)
 			return 0;
@@ -1726,6 +1741,7 @@ static void sdhci_tegra_program_stream_id(struct sdhci_host *host)
 
 static int sdhci_tegra_probe(struct platform_device *pdev)
 {
+	struct device_node *np = pdev->dev.of_node;
 	const struct sdhci_tegra_soc_data *soc_data;
 	struct sdhci_host *host;
 	struct sdhci_pltfm_host *pltfm_host;
@@ -1874,6 +1890,20 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
 		usleep_range(2000, 4000);
 	}
 
+	tegra_host->volt_switch_gpio = of_get_named_gpio(np,
+			"nvidia,voltage-switch-gpio", 0);
+	if (gpio_is_valid(tegra_host->volt_switch_gpio)) {
+		rc = gpio_request(tegra_host->volt_switch_gpio, "sdhci_power");
+		if (rc)
+			dev_err(mmc_dev(host->mmc),
+				"failed to allocate gpio for voltage switch, "
+				"err: %d\n", rc);
+		gpio_direction_output(tegra_host->volt_switch_gpio, 1);
+		gpio_set_value(tegra_host->volt_switch_gpio, 1);
+		dev_info(mmc_dev(host->mmc),
+				"3.3V set initially by voltage switch gpio\n");
+	}
+
 	rc = sdhci_tegra_add_host(host);
 	if (rc)
 		goto err_add_host;