drm/msm/dsi/phy: Protect PHY_CMN_CLK_CFG1 against clock driver

PHY_CMN_CLK_CFG1 register is updated by the PHY driver and by a mux
clock from Common Clock Framework:
devm_clk_hw_register_mux_parent_hws().  There could be a path leading to
concurrent and conflicting updates between PHY driver and clock
framework, e.g. changing the mux and enabling PLL clocks.

Add dedicated spinlock to be sure all PHY_CMN_CLK_CFG1 updates are
synchronized.

While shuffling the code, define and use PHY_CMN_CLK_CFG1 bitfields to
make the code more readable and obvious.

Fixes: 1ef7c99 ("drm/msm/dsi: add support for 7nm DSI PHY/PLL")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/637378/
Link: https://lore.kernel.org/r/20250214-drm-msm-phy-pll-cfg-reg-v3-2-0943b850722c@linaro.org
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>

Author: krzk

drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c

@@ -83,6 +83,9 @@ struct dsi_pll_7nm {
 	/* protects REG_DSI_7nm_PHY_CMN_CLK_CFG0 register */
 	spinlock_t postdiv_lock;
 
+	/* protects REG_DSI_7nm_PHY_CMN_CLK_CFG1 register */
+	spinlock_t pclk_mux_lock;
+
 	struct pll_7nm_cached_state cached_state;
 
 	struct dsi_pll_7nm *slave;
@@ -381,22 +384,32 @@ static void dsi_pll_cmn_clk_cfg0_write(struct dsi_pll_7nm *pll, u32 val)
 	spin_unlock_irqrestore(&pll->postdiv_lock, flags);
 }
 
-static void dsi_pll_disable_global_clk(struct dsi_pll_7nm *pll)
+static void dsi_pll_cmn_clk_cfg1_update(struct dsi_pll_7nm *pll, u32 mask,
+					u32 val)
 {
+	unsigned long flags;
 	u32 data;
 
+	spin_lock_irqsave(&pll->pclk_mux_lock, flags);
 	data = readl(pll->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
-	writel(data & ~BIT(5), pll->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
+	data &= ~mask;
+	data |= val & mask;
+
+	writel(data, pll->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
+	spin_unlock_irqrestore(&pll->pclk_mux_lock, flags);
+}
+
+static void dsi_pll_disable_global_clk(struct dsi_pll_7nm *pll)
+{
+	dsi_pll_cmn_clk_cfg1_update(pll, DSI_7nm_PHY_CMN_CLK_CFG1_CLK_EN, 0);
 }
 
 static void dsi_pll_enable_global_clk(struct dsi_pll_7nm *pll)
 {
-	u32 data;
+	u32 cfg_1 = DSI_7nm_PHY_CMN_CLK_CFG1_CLK_EN | DSI_7nm_PHY_CMN_CLK_CFG1_CLK_EN_SEL;
 
 	writel(0x04, pll->phy->base + REG_DSI_7nm_PHY_CMN_CTRL_3);
-
-	data = readl(pll->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
-	writel(data | BIT(5) | BIT(4), pll->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
+	dsi_pll_cmn_clk_cfg1_update(pll, cfg_1, cfg_1);
 }
 
 static void dsi_pll_phy_dig_reset(struct dsi_pll_7nm *pll)
@@ -574,7 +587,6 @@ static int dsi_7nm_pll_restore_state(struct msm_dsi_phy *phy)
 {
 	struct dsi_pll_7nm *pll_7nm = to_pll_7nm(phy->vco_hw);
 	struct pll_7nm_cached_state *cached = &pll_7nm->cached_state;
-	void __iomem *phy_base = pll_7nm->phy->base;
 	u32 val;
 	int ret;
 
@@ -586,11 +598,7 @@ static int dsi_7nm_pll_restore_state(struct msm_dsi_phy *phy)
 	dsi_pll_cmn_clk_cfg0_write(pll_7nm,
 				   DSI_7nm_PHY_CMN_CLK_CFG0_DIV_CTRL_3_0(cached->bit_clk_div) |
 				   DSI_7nm_PHY_CMN_CLK_CFG0_DIV_CTRL_7_4(cached->pix_clk_div));
-
-	val = readl(phy_base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
-	val &= ~0x3;
-	val |= cached->pll_mux;
-	writel(val, phy_base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
+	dsi_pll_cmn_clk_cfg1_update(pll_7nm, 0x3, cached->pll_mux);
 
 	ret = dsi_pll_7nm_vco_set_rate(phy->vco_hw,
 			pll_7nm->vco_current_rate,
@@ -743,7 +751,7 @@ static int pll_7nm_register(struct dsi_pll_7nm *pll_7nm, struct clk_hw **provide
 					pll_by_2_bit,
 				}), 2, 0, pll_7nm->phy->base +
 					REG_DSI_7nm_PHY_CMN_CLK_CFG1,
-				0, 1, 0, NULL);
+				0, 1, 0, &pll_7nm->pclk_mux_lock);
 		if (IS_ERR(hw)) {
 			ret = PTR_ERR(hw);
 			goto fail;
@@ -788,6 +796,7 @@ static int dsi_pll_7nm_init(struct msm_dsi_phy *phy)
 	pll_7nm_list[phy->id] = pll_7nm;
 
 	spin_lock_init(&pll_7nm->postdiv_lock);
+	spin_lock_init(&pll_7nm->pclk_mux_lock);
 
 	pll_7nm->phy = phy;
 

drivers/gpu/drm/msm/registers/display/dsi_phy_7nm.xml

@@ -13,7 +13,10 @@ xsi:schemaLocation="https://gitlab.freedesktop.org/freedreno/ rules-fd.xsd">
 		<bitfield name="DIV_CTRL_3_0" low="0" high="3" type="uint"/>
 		<bitfield name="DIV_CTRL_7_4" low="4" high="7" type="uint"/>
 	</reg32>
-	<reg32 offset="0x00014" name="CLK_CFG1"/>
+	<reg32 offset="0x00014" name="CLK_CFG1">
+		<bitfield name="CLK_EN" pos="5" type="boolean"/>
+		<bitfield name="CLK_EN_SEL" pos="4" type="boolean"/>
+	</reg32>
 	<reg32 offset="0x00018" name="GLBL_CTRL"/>
 	<reg32 offset="0x0001c" name="RBUF_CTRL"/>
 	<reg32 offset="0x00020" name="VREG_CTRL_0"/>