1 files changed, 74 insertions, 6 deletions

diff --git a/drivers/clk/imx/clk-lpcg-scu.c b/drivers/clk/imx/clk-lpcg-scu.c
index a73a799fb777..438611cd26ae 100644
--- a/drivers/clk/imx/clk-lpcg-scu.c
+++ b/drivers/clk/imx/clk-lpcg-scu.c
@@ -5,6 +5,7 @@
  */
 
 #include <linux/clk-provider.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/slab.h>
@@ -33,10 +34,38 @@ struct clk_lpcg_scu {
 	void __iomem *reg;
 	u8 bit_idx;
 	bool hw_gate;
+
+	/* for state save&restore */
+	u32 state;
 };
 
 #define to_clk_lpcg_scu(_hw) container_of(_hw, struct clk_lpcg_scu, hw)
 
+/* e10858 -LPCG clock gating register synchronization errata */
+static void do_lpcg_workaround(u32 rate, void __iomem *reg, u32 val)
+{
+	writel(val, reg);
+
+	if (rate >= 24000000 || rate == 0) {
+		u32 reg1;
+
+		/*
+		 * The time taken to access the LPCG registers from the AP core
+		 * through the interconnect is longer than the minimum delay
+		 * of 4 clock cycles required by the errata.
+		 * Adding a readl will provide sufficient delay to prevent
+		 * back-to-back writes.
+		 */
+		reg1 = readl(reg);
+	} else {
+		/*
+		 * For clocks running below 24MHz, wait a minimum of
+		 * 4 clock cycles.
+		 */
+		ndelay(4 * (DIV_ROUND_UP(1000000000, rate)));
+	}
+}
+
 static int clk_lpcg_scu_enable(struct clk_hw *hw)
 {
 	struct clk_lpcg_scu *clk = to_clk_lpcg_scu(hw);
@@ -53,7 +82,8 @@ static int clk_lpcg_scu_enable(struct clk_hw *hw)
 		val |= CLK_GATE_SCU_LPCG_HW_SEL;
 
 	reg |= val << clk->bit_idx;
-	writel(reg, clk->reg);
+
+	do_lpcg_workaround(clk_hw_get_rate(hw), clk->reg, reg);
 
 	spin_unlock_irqrestore(&imx_lpcg_scu_lock, flags);
 
@@ -70,7 +100,7 @@ static void clk_lpcg_scu_disable(struct clk_hw *hw)
 
 	reg = readl_relaxed(clk->reg);
 	reg &= ~(CLK_GATE_SCU_LPCG_MASK << clk->bit_idx);
-	writel(reg, clk->reg);
+	do_lpcg_workaround(clk_hw_get_rate(hw), clk->reg, reg);
 
 	spin_unlock_irqrestore(&imx_lpcg_scu_lock, flags);
 }
@@ -79,10 +109,11 @@ static const struct clk_ops clk_lpcg_scu_ops = {
 	.enable = clk_lpcg_scu_enable,
 	.disable = clk_lpcg_scu_disable,
 };
+EXPORT_SYMBOL_GPL(imx_clk_lpcg_scu_pm_ops);
 
-struct clk_hw *imx_clk_lpcg_scu(const char *name, const char *parent_name,
-				unsigned long flags, void __iomem *reg,
-				u8 bit_idx, bool hw_gate)
+struct clk_hw *__imx_clk_lpcg_scu(struct device *dev, const char *name,
+				  const char *parent_name, unsigned long flags,
+				  void __iomem *reg, u8 bit_idx, bool hw_gate)
 {
 	struct clk_lpcg_scu *clk;
 	struct clk_init_data init;
@@ -106,11 +137,48 @@ struct clk_hw *imx_clk_lpcg_scu(const char *name, const char *parent_name,
 	clk->hw.init = &init;
 
 	hw = &clk->hw;
-	ret = clk_hw_register(NULL, hw);
+	ret = clk_hw_register(dev, hw);
 	if (ret) {
 		kfree(clk);
 		hw = ERR_PTR(ret);
 	}
 
+	if (dev)
+		dev_set_drvdata(dev, clk);
+
 	return hw;
 }
+EXPORT_SYMBOL_GPL(__imx_clk_lpcg_scu);
+
+int __maybe_unused imx_clk_lpcg_scu_suspend(struct device *dev)
+{
+	struct clk_lpcg_scu *clk = dev_get_drvdata(dev);
+
+	if (!strncmp("hdmi_lpcg", clk_hw_get_name(&clk->hw), strlen("hdmi_lpcg")))
+		return 0;
+
+	clk->state = readl_relaxed(clk->reg);
+	dev_dbg(dev, "save lpcg state 0x%x\n", clk->state);
+
+	return 0;
+}
+
+int __maybe_unused imx_clk_lpcg_scu_resume(struct device *dev)
+{
+	struct clk_lpcg_scu *clk = dev_get_drvdata(dev);
+
+	if (!strncmp("hdmi_lpcg", clk_hw_get_name(&clk->hw), strlen("hdmi_lpcg")))
+		return 0;
+
+	/* FIXME: double write in case a failure */
+	writel(clk->state, clk->reg);
+	do_lpcg_workaround(0, clk->reg, clk->state);
+	dev_dbg(dev, "restore lpcg state 0x%x\n", clk->state);
+
+	return 0;
+}
+
+const struct dev_pm_ops imx_clk_lpcg_scu_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_clk_lpcg_scu_suspend,
+				      imx_clk_lpcg_scu_resume)
+};