clk: stm32mp1: new compatible for secure RCC support

Platform STM32MP1 can be used in configuration where some clock
resources cannot be accessed by Linux kernel when executing in non-secure
state of the CPU(s).
In such configuration, the RCC clock driver must not register clocks
it cannot access.
They are expected to be registered from another clock driver such
as the SCMI clock driver.
This change uses specific compatible string "st,stm32mp1-rcc-secure"
to specify RCC clock driver configuration where RCC is secure.

Signed-off-by: Etienne Carriere <[email protected]>
Signed-off-by: Gabriel Fernandez <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Stephen Boyd <[email protected]>

Author: Gabriel-Fernandz

drivers/clk/Kconfig

@@ -335,6 +335,16 @@ config COMMON_CLK_STM32MP157
 	help
 	  Support for stm32mp157 SoC family clocks
 
+config COMMON_CLK_STM32MP157_SCMI
+	bool "stm32mp157 Clock driver with Trusted Firmware"
+	depends on COMMON_CLK_STM32MP157
+	select COMMON_CLK_SCMI
+	select ARM_SCMI_PROTOCOL
+	default y
+	help
+	  Support for stm32mp157 SoC family clocks with Trusted Firmware using
+	  SCMI protocol.
+
 config COMMON_CLK_STM32F
 	def_bool COMMON_CLK && (MACH_STM32F429 || MACH_STM32F469 || MACH_STM32F746)
 	help

drivers/clk/clk-stm32mp1.c

@@ -2056,11 +2056,61 @@ static const struct clock_config stm32mp1_clock_cfg[] = {
 		  _DIV(RCC_DBGCFGR, 0, 3, 0, ck_trace_div_table)),
 };
 
+static const u32 stm32mp1_clock_secured[] = {
+	CK_HSE,
+	CK_HSI,
+	CK_CSI,
+	CK_LSI,
+	CK_LSE,
+	PLL1,
+	PLL2,
+	PLL1_P,
+	PLL2_P,
+	PLL2_Q,
+	PLL2_R,
+	CK_MPU,
+	CK_AXI,
+	SPI6,
+	I2C4,
+	I2C6,
+	USART1,
+	RTCAPB,
+	TZC1,
+	TZC2,
+	TZPC,
+	IWDG1,
+	BSEC,
+	STGEN,
+	GPIOZ,
+	CRYP1,
+	HASH1,
+	RNG1,
+	BKPSRAM,
+	RNG1_K,
+	STGEN_K,
+	SPI6_K,
+	I2C4_K,
+	I2C6_K,
+	USART1_K,
+	RTC,
+};
+
+static bool stm32_check_security(const struct clock_config *cfg)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(stm32mp1_clock_secured); i++)
+		if (cfg->id == stm32mp1_clock_secured[i])
+			return true;
+	return false;
+}
+
 struct stm32_rcc_match_data {
 	const struct clock_config *cfg;
 	unsigned int num;
 	unsigned int maxbinding;
 	u32 clear_offset;
+	bool (*check_security)(const struct clock_config *cfg);
 };
 
 static struct stm32_rcc_match_data stm32mp1_data = {
@@ -2070,11 +2120,23 @@ static struct stm32_rcc_match_data stm32mp1_data = {
 	.clear_offset	= RCC_CLR,
 };
 
+static struct stm32_rcc_match_data stm32mp1_data_secure = {
+	.cfg		= stm32mp1_clock_cfg,
+	.num		= ARRAY_SIZE(stm32mp1_clock_cfg),
+	.maxbinding	= STM32MP1_LAST_CLK,
+	.clear_offset	= RCC_CLR,
+	.check_security = &stm32_check_security
+};
+
 static const struct of_device_id stm32mp1_match_data[] = {
 	{
 		.compatible = "st,stm32mp1-rcc",
 		.data = &stm32mp1_data,
 	},
+	{
+		.compatible = "st,stm32mp1-rcc-secure",
+		.data = &stm32mp1_data_secure,
+	},
 	{ }
 };
 MODULE_DEVICE_TABLE(of, stm32mp1_match_data);
@@ -2234,6 +2296,9 @@ static int stm32_rcc_clock_init(struct device *dev, void __iomem *base,
 		hws[n] = ERR_PTR(-ENOENT);
 
 	for (n = 0; n < data->num; n++) {
+		if (data->check_security && data->check_security(&data->cfg[n]))
+			continue;
+
 		err = stm32_register_hw_clk(dev, clk_data, base, &rlock,
 					    &data->cfg[n]);
 		if (err) {
@@ -2301,11 +2366,45 @@ static int stm32mp1_rcc_init(struct device *dev)
 	return ret;
 }
 
+static int get_clock_deps(struct device *dev)
+{
+	static const char * const clock_deps_name[] = {
+		"hsi", "hse", "csi", "lsi", "lse",
+	};
+	size_t deps_size = sizeof(struct clk *) * ARRAY_SIZE(clock_deps_name);
+	struct clk **clk_deps;
+	int i;
+
+	clk_deps = devm_kzalloc(dev, deps_size, GFP_KERNEL);
+	if (!clk_deps)
+		return -ENOMEM;
+
+	for (i = 0; i < ARRAY_SIZE(clock_deps_name); i++) {
+		struct clk *clk = of_clk_get_by_name(dev_of_node(dev),
+						     clock_deps_name[i]);
+
+		if (IS_ERR(clk)) {
+			if (PTR_ERR(clk) != -EINVAL && PTR_ERR(clk) != -ENOENT)
+				return PTR_ERR(clk);
+		} else {
+			/* Device gets a reference count on the clock */
+			clk_deps[i] = devm_clk_get(dev, __clk_get_name(clk));
+			clk_put(clk);
+		}
+	}
+
+	return 0;
+}
+
 static int stm32mp1_rcc_clocks_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	int ret = get_clock_deps(dev);
+
+	if (!ret)
+		ret = stm32mp1_rcc_init(dev);
 
-	return stm32mp1_rcc_init(dev);
+	return ret;
 }
 
 static int stm32mp1_rcc_clocks_remove(struct platform_device *pdev)