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From:   Prathamesh Shete <pshete@nvidia.com>
To:     <thierry.reding@gmail.com>, <linus.walleij@linaro.org>,
        <bgolaszewski@baylibre.com>, <jonathanh@nvidia.com>,
        <linux-gpio@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     <smangipudi@nvidia.com>, <pshete@nvidia.com>,
        <kyarlagadda@nvidia.com>, Manish Bhardwaj <mbhardwaj@nvidia.com>
Subject: [PATCH v3] gpio: tegra186: Check GPIO pin permission before access.
Date:   Fri, 7 Oct 2022 11:29:36 +0530
Message-ID: <20221007055936.5446-1-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 | 78 ++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/drivers/gpio/gpio-tegra186.c b/drivers/gpio/gpio-tegra186.c
index 54d9fa7da9c1..873b476ae8f1 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			0x00
+#define  TEGRA186_GPIO_VM_RW_MASK		0x03
+#define  TEGRA186_GPIO_SCR			0x04
+#define  TEGRA186_GPIO_SCR_PIN_SIZE		0x08
+#define  TEGRA186_GPIO_SCR_PORT_SIZE		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)
@@ -80,6 +96,7 @@ struct tegra_gpio_soc {
 	unsigned int num_pin_ranges;
 	const char *pinmux;
 	bool has_gte;
+	bool has_vm_support;
 };
 
 struct tegra_gpio {
@@ -129,6 +146,58 @@ 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_PORT_SIZE;
+
+	return gpio->secure + offset + pin * TEGRA186_GPIO_SCR_PIN_SIZE;
+}
+
+static inline bool tegra186_gpio_is_accessible(struct tegra_gpio *gpio, unsigned int pin)
+{
+	void __iomem *secure;
+	u32 value;
+
+	secure = tegra186_gpio_get_secure_base(gpio, pin);
+
+	if (gpio->soc->has_vm_support) {
+		value = readl(secure + TEGRA186_GPIO_VM);
+		if ((value & TEGRA186_GPIO_VM_RW_MASK) != TEGRA186_GPIO_VM_RW_MASK)
+			return false;
+	}
+
+	value = __raw_readl(secure + TEGRA186_GPIO_SCR);
+
+	if ((value & TEGRA186_GPIO_SCR_SEC_ENABLE) == 0)
+		return true;
+
+	if ((value & TEGRA186_GPIO_FULL_ACCESS) == TEGRA186_GPIO_FULL_ACCESS)
+		return true;
+
+	return false;
+}
+
+static int tegra186_init_valid_mask(struct gpio_chip *chip,
+		unsigned long *valid_mask, unsigned int ngpios)
+{
+	struct tegra_gpio *gpio = gpiochip_get_data(chip);
+	unsigned int j;
+
+	for (j = 0; j < ngpios; j++) {
+		if (!tegra186_gpio_is_accessible(gpio, j))
+			clear_bit(j, valid_mask);
+	}
+	return 0;
+}
+
 static int tegra186_gpio_get_direction(struct gpio_chip *chip,
 				       unsigned int offset)
 {
@@ -818,6 +887,7 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
 	gpio->gpio.set = tegra186_gpio_set;
 	gpio->gpio.set_config = tegra186_gpio_set_config;
 	gpio->gpio.add_pin_ranges = tegra186_gpio_add_pin_ranges;
+	gpio->gpio.init_valid_mask = tegra186_init_valid_mask;
 	if (gpio->soc->has_gte) {
 		gpio->gpio.en_hw_timestamp = tegra186_gpio_en_hw_ts;
 		gpio->gpio.dis_hw_timestamp = tegra186_gpio_dis_hw_ts;
@@ -960,6 +1030,7 @@ static const struct tegra_gpio_soc tegra186_main_soc = {
 	.name = "tegra186-gpio",
 	.instance = 0,
 	.num_irqs_per_bank = 1,
+	.has_vm_support = false,
 };
 
 #define TEGRA186_AON_GPIO_PORT(_name, _bank, _port, _pins)	\
@@ -987,6 +1058,7 @@ static const struct tegra_gpio_soc tegra186_aon_soc = {
 	.name = "tegra186-gpio-aon",
 	.instance = 1,
 	.num_irqs_per_bank = 1,
+	.has_vm_support = false,
 };
 
 #define TEGRA194_MAIN_GPIO_PORT(_name, _bank, _port, _pins)	\
@@ -1042,6 +1114,7 @@ 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 +1140,7 @@ 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)	\
@@ -1111,6 +1185,7 @@ static const struct tegra_gpio_soc tegra234_main_soc = {
 	.name = "tegra234-gpio",
 	.instance = 0,
 	.num_irqs_per_bank = 8,
+	.has_vm_support = true,
 };
 
 #define TEGRA234_AON_GPIO_PORT(_name, _bank, _port, _pins)	\
@@ -1136,6 +1211,7 @@ static const struct tegra_gpio_soc tegra234_aon_soc = {
 	.name = "tegra234-gpio-aon",
 	.instance = 1,
 	.num_irqs_per_bank = 8,
+	.has_vm_support = false,
 };
 
 #define TEGRA241_MAIN_GPIO_PORT(_name, _bank, _port, _pins)	\
@@ -1166,6 +1242,7 @@ static const struct tegra_gpio_soc tegra241_main_soc = {
 	.name = "tegra241-gpio",
 	.instance = 0,
 	.num_irqs_per_bank = 8,
+	.has_vm_support = false,
 };
 
 #define TEGRA241_AON_GPIO_PORT(_name, _bank, _port, _pins)	\
@@ -1187,6 +1264,7 @@ static const struct tegra_gpio_soc tegra241_aon_soc = {
 	.name = "tegra241-gpio-aon",
 	.instance = 1,
 	.num_irqs_per_bank = 8,
+	.has_vm_support = false,
 };
 
 static const struct of_device_id tegra186_gpio_of_match[] = {
-- 
2.17.1