clk: tegra: clk-super: Fix to enable PLLP branches to CPU

This patch has a fix to enable PLLP branches to CPU before changing
the CPU cluster clock source to PLLP for Gen5 Super clock and
disables PLLP branches to CPU when not in use.

During system suspend entry and exit, CPU source will be switched
to PLLP and this needs PLLP branches to be enabled to CPU prior to
the switch.

On system resume, warmboot code enables PLLP branches to CPU and
powers up the CPU with PLLP clock source.
Acked-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/clk/tegra/clk-super.c

@@ -28,6 +28,9 @@
 #define super_state_to_src_shift(m, s) ((m->width * s))
 #define super_state_to_src_mask(m) (((1 << m->width) - 1))
 
+#define CCLK_SRC_PLLP_OUT0 4
+#define CCLK_SRC_PLLP_OUT4 5
+
 static u8 clk_super_get_parent(struct clk_hw *hw)
 {
 	struct tegra_clk_super_mux *mux = to_clk_super_mux(hw);
@@ -97,12 +100,23 @@ static int clk_super_set_parent(struct clk_hw *hw, u8 index)
 		if (index == mux->div2_index)
 			index = mux->pllx_index;
 	}
+
+	/* enable PLLP branches to CPU before selecting PLLP source */
+	if ((mux->flags & TEGRA210_CPU_CLK) &&
+	    (index == CCLK_SRC_PLLP_OUT0 || index == CCLK_SRC_PLLP_OUT4))
+		tegra_clk_set_pllp_out_cpu(true);
+
 	val &= ~((super_state_to_src_mask(mux)) << shift);
 	val |= (index & (super_state_to_src_mask(mux))) << shift;
 
 	writel_relaxed(val, mux->reg);
 	udelay(2);
 
+	/* disable PLLP branches to CPU if not used */
+	if ((mux->flags & TEGRA210_CPU_CLK) &&
+	    index != CCLK_SRC_PLLP_OUT0 && index != CCLK_SRC_PLLP_OUT4)
+		tegra_clk_set_pllp_out_cpu(false);
+
 out:
 	if (mux->lock)
 		spin_unlock_irqrestore(mux->lock, flags);

drivers/clk/tegra/clk-tegra-super-gen4.c

@@ -180,7 +180,7 @@ static void __init tegra_super_clk_init(void __iomem *clk_base,
 					gen_info->num_cclk_g_parents,
 					CLK_SET_RATE_PARENT,
 					clk_base + CCLKG_BURST_POLICY,
-					0, 4, 8, 0, NULL);
+					TEGRA210_CPU_CLK, 4, 8, 0, NULL);
 		} else {
 			clk = tegra_clk_register_super_mux("cclk_g",
 					gen_info->cclk_g_parents,
@@ -196,6 +196,11 @@ static void __init tegra_super_clk_init(void __iomem *clk_base,
 	dt_clk = tegra_lookup_dt_id(tegra_clk_cclk_lp, tegra_clks);
 	if (dt_clk) {
 		if (gen_info->gen == gen5) {
+			/*
+			 * TEGRA210_CPU_CLK flag is not needed for cclk_lp as
+			 * cluster switching is not currently supported on
+			 * Tegra210 and also cpu_lp is not used.
+			 */
 			clk = tegra_clk_register_super_mux("cclk_lp",
 					gen_info->cclk_lp_parents,
 					gen_info->num_cclk_lp_parents,

drivers/clk/tegra/clk.c

@@ -23,6 +23,7 @@
 #define CLK_OUT_ENB_W			0x364
 #define CLK_OUT_ENB_X			0x280
 #define CLK_OUT_ENB_Y			0x298
+#define CLK_ENB_PLLP_OUT_CPU		BIT(31)
 #define CLK_OUT_ENB_SET_L		0x320
 #define CLK_OUT_ENB_CLR_L		0x324
 #define CLK_OUT_ENB_SET_H		0x328
@@ -199,6 +200,19 @@ const struct tegra_clk_periph_regs *get_reg_bank(int clkid)
 	}
 }
 
+void tegra_clk_set_pllp_out_cpu(bool enable)
+{
+	u32 val;
+
+	val = readl_relaxed(clk_base + CLK_OUT_ENB_Y);
+	if (enable)
+		val |= CLK_ENB_PLLP_OUT_CPU;
+	else
+		val &= ~CLK_ENB_PLLP_OUT_CPU;
+
+	writel_relaxed(val, clk_base + CLK_OUT_ENB_Y);
+}
+
 struct clk ** __init tegra_clk_init(void __iomem *regs, int num, int banks)
 {
 	clk_base = regs;

drivers/clk/tegra/clk.h

@@ -669,6 +669,9 @@ struct clk *tegra_clk_register_periph_data(void __iomem *clk_base,
  * Flags:
  * TEGRA_DIVIDER_2 - LP cluster has additional divider. This flag indicates
  *     that this is LP cluster clock.
+ * TEGRA210_CPU_CLK - This flag is used to identify CPU cluster for gen5
+ * super mux parent using PLLP branches. To use PLLP branches to CPU, need
+ * to configure additional bit PLLP_OUT_CPU in the clock registers.
  */
 struct tegra_clk_super_mux {
 	struct clk_hw	hw;
@@ -685,6 +688,7 @@ struct tegra_clk_super_mux {
 #define to_clk_super_mux(_hw) container_of(_hw, struct tegra_clk_super_mux, hw)
 
 #define TEGRA_DIVIDER_2 BIT(0)
+#define TEGRA210_CPU_CLK BIT(1)
 
 extern const struct clk_ops tegra_clk_super_ops;
 struct clk *tegra_clk_register_super_mux(const char *name,
@@ -830,6 +834,7 @@ int tegra_pll_p_div_to_hw(struct tegra_clk_pll *pll, u8 p_div);
 int div_frac_get(unsigned long rate, unsigned parent_rate, u8 width,
 		 u8 frac_width, u8 flags);
 void tegra_clk_osc_resume(void __iomem *clk_base);
+void tegra_clk_set_pllp_out_cpu(bool enable);
 
 
 /* Combined read fence with delay */