clk: stm32mp13: add safe mux management

Some muxes need to set a the safe position when clock is off.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@foss.st.com>
Link: https://lore.kernel.org/r/20220516070600.7692-12-gabriel.fernandez@foss.st.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: Gabriel-Fernandz

drivers/clk/stm32/clk-stm32-core.c

@@ -495,6 +495,54 @@ static int clk_stm32_composite_is_enabled(struct clk_hw *hw)
 	return stm32_gate_is_enabled(composite->base, composite->clock_data, composite->gate_id);
 }
 
+#define MUX_SAFE_POSITION 0
+
+static int clk_stm32_has_safe_mux(struct clk_hw *hw)
+{
+	struct clk_stm32_composite *composite = to_clk_stm32_composite(hw);
+	const struct stm32_mux_cfg *mux = &composite->clock_data->muxes[composite->mux_id];
+
+	return !!(mux->flags & MUX_SAFE);
+}
+
+static void clk_stm32_set_safe_position_mux(struct clk_hw *hw)
+{
+	struct clk_stm32_composite *composite = to_clk_stm32_composite(hw);
+
+	if (!clk_stm32_composite_is_enabled(hw)) {
+		unsigned long flags = 0;
+
+		if (composite->clock_data->is_multi_mux) {
+			struct clk_hw *other_mux_hw = NULL;
+
+			other_mux_hw = composite->clock_data->is_multi_mux(hw);
+
+			if (!other_mux_hw || clk_stm32_composite_is_enabled(other_mux_hw))
+				return;
+		}
+
+		spin_lock_irqsave(composite->lock, flags);
+
+		stm32_mux_set_parent(composite->base, composite->clock_data,
+				     composite->mux_id, MUX_SAFE_POSITION);
+
+		spin_unlock_irqrestore(composite->lock, flags);
+	}
+}
+
+static void clk_stm32_safe_restore_position_mux(struct clk_hw *hw)
+{
+	struct clk_stm32_composite *composite = to_clk_stm32_composite(hw);
+	int sel = clk_hw_get_parent_index(hw);
+	unsigned long flags = 0;
+
+	spin_lock_irqsave(composite->lock, flags);
+
+	stm32_mux_set_parent(composite->base, composite->clock_data, composite->mux_id, sel);
+
+	spin_unlock_irqrestore(composite->lock, flags);
+}
+
 static void clk_stm32_composite_gate_endisable(struct clk_hw *hw, int enable)
 {
 	struct clk_stm32_composite *composite = to_clk_stm32_composite(hw);
@@ -516,6 +564,9 @@ static int clk_stm32_composite_gate_enable(struct clk_hw *hw)
 
 	clk_stm32_composite_gate_endisable(hw, 1);
 
+	if (composite->mux_id != NO_STM32_MUX && clk_stm32_has_safe_mux(hw))
+		clk_stm32_safe_restore_position_mux(hw);
+
 	return 0;
 }
 
@@ -527,6 +578,9 @@ static void clk_stm32_composite_gate_disable(struct clk_hw *hw)
 		return;
 
 	clk_stm32_composite_gate_endisable(hw, 0);
+
+	if (composite->mux_id != NO_STM32_MUX && clk_stm32_has_safe_mux(hw))
+		clk_stm32_set_safe_position_mux(hw);
 }
 
 static void clk_stm32_composite_disable_unused(struct clk_hw *hw)

drivers/clk/stm32/clk-stm32-core.h

@@ -84,6 +84,7 @@ int stm32_rcc_init(struct device *dev, const struct of_device_id *match_data,
 
 /* MUX define */
 #define MUX_NO_RDY		0xFF
+#define MUX_SAFE		BIT(7)
 
 /* DIV define */
 #define DIV_NO_RDY		0xFF

drivers/clk/stm32/clk-stm32mp13.c

@@ -359,6 +359,9 @@ enum enum_mux_cfg {
 #define CFG_MUX(_id, _offset, _shift, _witdh)\
 	_CFG_MUX(_id, _offset, _shift, _witdh, MUX_NO_RDY, 0)
 
+#define CFG_MUX_SAFE(_id, _offset, _shift, _witdh)\
+	_CFG_MUX(_id, _offset, _shift, _witdh, MUX_NO_RDY, MUX_SAFE)
+
 static const struct stm32_mux_cfg stm32mp13_muxes[] = {
 	CFG_MUX(MUX_I2C12,	RCC_I2C12CKSELR,	0, 3),
 	CFG_MUX(MUX_LPTIM45,	RCC_LPTIM45CKSELR,	0, 3),
@@ -394,10 +397,10 @@ static const struct stm32_mux_cfg stm32mp13_muxes[] = {
 	CFG_MUX(MUX_UART6,	RCC_UART6CKSELR,	0, 3),
 	CFG_MUX(MUX_USBO,	RCC_USBCKSELR,		4, 1),
 	CFG_MUX(MUX_USBPHY,	RCC_USBCKSELR,		0, 2),
-	CFG_MUX(MUX_FMC,	RCC_FMCCKSELR,		0, 2),
-	CFG_MUX(MUX_QSPI,	RCC_QSPICKSELR,		0, 2),
-	CFG_MUX(MUX_SDMMC1,	RCC_SDMMC12CKSELR,	0, 3),
-	CFG_MUX(MUX_SDMMC2,	RCC_SDMMC12CKSELR,	3, 3),
+	CFG_MUX_SAFE(MUX_FMC,	RCC_FMCCKSELR,		0, 2),
+	CFG_MUX_SAFE(MUX_QSPI,	RCC_QSPICKSELR,		0, 2),
+	CFG_MUX_SAFE(MUX_SDMMC1, RCC_SDMMC12CKSELR,	0, 3),
+	CFG_MUX_SAFE(MUX_SDMMC2, RCC_SDMMC12CKSELR,	3, 3),
 };
 
 struct clk_stm32_securiy {