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From:   Prathamesh Shete <pshete@nvidia.com>
To:     <linus.walleij@linaro.org>, <bgolaszewski@baylibre.com>,
        <linux-gpio@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <jonathanh@nvidia.com>,
        <thierry.reding@gmail.com>
CC:     <smangipudi@nvidia.com>, <pshete@nvidia.com>,
        <kyarlagadda@nvidia.com>, Manish Bhardwaj <mbhardwaj@nvidia.com>
Subject: [PATCH] gpio: tegra186: Check GPIO pin permission before access.
Date:   Wed, 14 Sep 2022 17:51:10 +0530
Message-ID: <20220914122110.7246-1-pshete@nvidia.com>
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This change checks if we have the necessary permission to
access the GPIO. For devices that have support for virtualisation
we need to check both the TEGRA186_GPIO_VM_REG and the
TEGRA186_GPIO_SCR_REG registers. For device that do not have
virtualisation support for GPIOs we only need to check the
TEGRA186_GPIO_SCR_REG register.

Signed-off-by: Manish Bhardwaj <mbhardwaj@nvidia.com>
Signed-off-by: Prathamesh Shete <pshete@nvidia.com>
---
 drivers/gpio/gpio-tegra186.c | 71 ++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/drivers/gpio/gpio-tegra186.c b/drivers/gpio/gpio-tegra186.c
index 54d9fa7da9c1..e6fc3c9b1e9f 100644
--- a/drivers/gpio/gpio-tegra186.c
+++ b/drivers/gpio/gpio-tegra186.c
@@ -26,6 +26,22 @@
 
 #define TEGRA186_GPIO_INT_ROUTE_MAPPING(p, x) (0x14 + (p) * 0x20 + (x) * 4)
 
+#define  TEGRA186_GPIO_VM_REG			0x00
+#define  TEGRA186_GPIO_VM_RW_MASK		0x03
+#define  TEGRA186_GPIO_SCR_REG			0x04
+#define  TEGRA186_GPIO_SCR_DIFF			0x08
+#define  TEGRA186_GPIO_SCR_BASE_DIFF		0x40
+#define  TEGRA186_GPIO_SCR_SEC_WEN		BIT(28)
+#define  TEGRA186_GPIO_SCR_SEC_REN		BIT(27)
+#define  TEGRA186_GPIO_SCR_SEC_G1W		BIT(9)
+#define  TEGRA186_GPIO_SCR_SEC_G1R		BIT(1)
+#define  TEGRA186_GPIO_FULL_ACCESS		(TEGRA186_GPIO_SCR_SEC_WEN | \
+						 TEGRA186_GPIO_SCR_SEC_REN | \
+						 TEGRA186_GPIO_SCR_SEC_G1R | \
+						 TEGRA186_GPIO_SCR_SEC_G1W)
+#define  TEGRA186_GPIO_SCR_SEC_ENABLE		(TEGRA186_GPIO_SCR_SEC_WEN | \
+						 TEGRA186_GPIO_SCR_SEC_REN)
+
 /* control registers */
 #define TEGRA186_GPIO_ENABLE_CONFIG 0x00
 #define  TEGRA186_GPIO_ENABLE_CONFIG_ENABLE BIT(0)
@@ -77,6 +93,7 @@ struct tegra_gpio_soc {
 	unsigned int num_irqs_per_bank;
 
 	const struct tegra186_pin_range *pin_ranges;
+	bool has_vm_support;
 	unsigned int num_pin_ranges;
 	const char *pinmux;
 	bool has_gte;
@@ -129,6 +146,45 @@ static void __iomem *tegra186_gpio_get_base(struct tegra_gpio *gpio,
 	return gpio->base + offset + pin * 0x20;
 }
 
+static void __iomem *tegra186_gpio_get_secure_base(struct tegra_gpio *gpio,
+					    unsigned int pin)
+{
+	const struct tegra_gpio_port *port;
+	unsigned int offset;
+
+	port = tegra186_gpio_get_port(gpio, &pin);
+	if (!port)
+		return NULL;
+
+	offset = port->bank * 0x1000 + port->port * TEGRA186_GPIO_SCR_BASE_DIFF;
+
+	return gpio->secure + offset + pin * TEGRA186_GPIO_SCR_DIFF;
+}
+
+static inline bool tegra186_gpio_is_accessible(struct tegra_gpio *gpio, u32 pin)
+{
+	void __iomem *secure;
+	u32 val;
+
+	secure = tegra186_gpio_get_secure_base(gpio, pin);
+
+	if (gpio->soc->has_vm_support) {
+		val = readl(secure + TEGRA186_GPIO_VM_REG);
+		if ((val & TEGRA186_GPIO_VM_RW_MASK) != TEGRA186_GPIO_VM_RW_MASK)
+			return false;
+	}
+
+	val = __raw_readl(secure + TEGRA186_GPIO_SCR_REG);
+
+	if ((val & TEGRA186_GPIO_SCR_SEC_ENABLE) == 0)
+		return true;
+
+	if ((val & TEGRA186_GPIO_FULL_ACCESS) == TEGRA186_GPIO_FULL_ACCESS)
+		return true;
+
+	return false;
+}
+
 static int tegra186_gpio_get_direction(struct gpio_chip *chip,
 				       unsigned int offset)
 {
@@ -136,6 +192,9 @@ static int tegra186_gpio_get_direction(struct gpio_chip *chip,
 	void __iomem *base;
 	u32 value;
 
+	if (!tegra186_gpio_is_accessible(gpio, offset))
+		return -EPERM;
+
 	base = tegra186_gpio_get_base(gpio, offset);
 	if (WARN_ON(base == NULL))
 		return -ENODEV;
@@ -154,6 +213,9 @@ static int tegra186_gpio_direction_input(struct gpio_chip *chip,
 	void __iomem *base;
 	u32 value;
 
+	if (!tegra186_gpio_is_accessible(gpio, offset))
+		return -EPERM;
+
 	base = tegra186_gpio_get_base(gpio, offset);
 	if (WARN_ON(base == NULL))
 		return -ENODEV;
@@ -177,6 +239,9 @@ static int tegra186_gpio_direction_output(struct gpio_chip *chip,
 	void __iomem *base;
 	u32 value;
 
+	if (!tegra186_gpio_is_accessible(gpio, offset))
+		return -EPERM;
+
 	/* configure output level first */
 	chip->set(chip, offset, level);
 
@@ -293,6 +358,10 @@ static void tegra186_gpio_set(struct gpio_chip *chip, unsigned int offset,
 	void __iomem *base;
 	u32 value;
 
+	if (!tegra186_gpio_is_accessible(gpio, offset)){
+		pr_err("GPIO not accessible\n");
+		return;
+	}
 	base = tegra186_gpio_get_base(gpio, offset);
 	if (WARN_ON(base == NULL))
 		return;
@@ -1042,6 +1111,7 @@ static const struct tegra_gpio_soc tegra194_main_soc = {
 	.num_pin_ranges = ARRAY_SIZE(tegra194_main_pin_ranges),
 	.pin_ranges = tegra194_main_pin_ranges,
 	.pinmux = "nvidia,tegra194-pinmux",
+	.has_vm_support = true,
 };
 
 #define TEGRA194_AON_GPIO_PORT(_name, _bank, _port, _pins)	\
@@ -1067,6 +1137,7 @@ static const struct tegra_gpio_soc tegra194_aon_soc = {
 	.instance = 1,
 	.num_irqs_per_bank = 8,
 	.has_gte = true,
+	.has_vm_support = false,
 };
 
 #define TEGRA234_MAIN_GPIO_PORT(_name, _bank, _port, _pins)	\
-- 
2.17.1