[PATCH V4 07/18] clk: tegra: save and restore CPU and System clocks context

[Sowjanya Komatineni <skomatineni@xxxxxxxxxx>]

During system suspend state, core power goes off and looses all the
CAR controller register settings.

This patch creates APIs for saving and restoring the context of Tegra
CPUG, CPULP and SCLK.

CPU and System clock context includes
- CPUG, CPULP, and SCLK burst policy settings for clock sourcea of all
  their normal states.
- SCLK divisor and System clock rate for restoring SCLK, AHB and APB
  rates on resume.
- OSC_DIV settings which are used as reference clock input to some PLLs.
- SPARE_REG and CLK_MASK settings.

These APIs are used in Tegra210 clock driver during suspend and resume
operation.

Acked-by: Thierry Reding <treding@xxxxxxxxxx>
Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
---
 drivers/clk/tegra/clk-tegra-super-gen4.c |  4 --
 drivers/clk/tegra/clk.c                  | 80 ++++++++++++++++++++++++++++++++
 drivers/clk/tegra/clk.h                  | 14 ++++++
 3 files changed, 94 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/tegra/clk-tegra-super-gen4.c b/drivers/clk/tegra/clk-tegra-super-gen4.c
index cdfe7c9697e1..ed69ec4d883e 100644
--- a/drivers/clk/tegra/clk-tegra-super-gen4.c
+++ b/drivers/clk/tegra/clk-tegra-super-gen4.c
@@ -19,10 +19,6 @@
 #define PLLX_MISC2 0x514
 #define PLLX_MISC3 0x518
 
-#define CCLKG_BURST_POLICY 0x368
-#define CCLKLP_BURST_POLICY 0x370
-#define SCLK_BURST_POLICY 0x028
-#define SYSTEM_CLK_RATE 0x030
 #define SCLK_DIVIDER 0x2c
 
 static DEFINE_SPINLOCK(sysrate_lock);
diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
index 573e3c967ae1..9e863362d2bf 100644
--- a/drivers/clk/tegra/clk.c
+++ b/drivers/clk/tegra/clk.c
@@ -70,6 +70,12 @@ static struct clk **clks;
 static int clk_num;
 static struct clk_onecell_data clk_data;
 
+static u32 cclkg_burst_policy_ctx[2];
+static u32 cclklp_burst_policy_ctx[2];
+static u32 sclk_burst_policy_ctx[2];
+static u32 sys_clk_divisor_ctx, system_rate_ctx;
+static u32 spare_ctx, misc_clk_enb_ctx, clk_arm_ctx;
+
 /* Handlers for SoC-specific reset lines */
 static int (*special_reset_assert)(unsigned long);
 static int (*special_reset_deassert)(unsigned long);
@@ -199,6 +205,80 @@ const struct tegra_clk_periph_regs *get_reg_bank(int clkid)
 	}
 }
 
+void tegra_cclkg_burst_policy_save_context(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < BURST_POLICY_REG_SIZE; i++)
+		cclkg_burst_policy_ctx[i] = readl_relaxed(clk_base +
+							  CCLKG_BURST_POLICY +
+							  (i * 4));
+}
+
+void tegra_cclkg_burst_policy_restore_context(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < BURST_POLICY_REG_SIZE; i++)
+		writel_relaxed(cclkg_burst_policy_ctx[i],
+			       clk_base + CCLKG_BURST_POLICY + (i * 4));
+
+	fence_udelay(2, clk_base);
+}
+
+void tegra_sclk_cclklp_burst_policy_save_context(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < BURST_POLICY_REG_SIZE; i++) {
+		cclklp_burst_policy_ctx[i] = readl_relaxed(clk_base +
+							  CCLKLP_BURST_POLICY +
+							  (i * 4));
+
+		sclk_burst_policy_ctx[i] = readl_relaxed(clk_base +
+							  SCLK_BURST_POLICY +
+							  (i * 4));
+	}
+
+	sys_clk_divisor_ctx = readl_relaxed(clk_base + SYS_CLK_DIV);
+	system_rate_ctx = readl_relaxed(clk_base + SYSTEM_CLK_RATE);
+	spare_ctx = readl_relaxed(clk_base + SPARE_REG0);
+	misc_clk_enb_ctx = readl_relaxed(clk_base + MISC_CLK_ENB);
+	clk_arm_ctx = readl_relaxed(clk_base + CLK_MASK_ARM);
+}
+
+void tegra_sclk_cpulp_burst_policy_restore_context(void)
+{
+	unsigned int i;
+	u32 val;
+
+	/*
+	 * resume SCLK and CPULP clocks
+	 * for SCLk, set safe dividers values first and then restore source
+	 * and dividers
+	 */
+
+	writel_relaxed(0x1, clk_base + SYSTEM_CLK_RATE);
+	val = readl_relaxed(clk_base + SYS_CLK_DIV);
+	if (val < sys_clk_divisor_ctx)
+		writel_relaxed(sys_clk_divisor_ctx, clk_base + SYS_CLK_DIV);
+
+	fence_udelay(2, clk_base);
+
+	for (i = 0; i < BURST_POLICY_REG_SIZE; i++) {
+		writel_relaxed(cclklp_burst_policy_ctx[i],
+			       clk_base + CCLKLP_BURST_POLICY + (i * 4));
+		writel_relaxed(sclk_burst_policy_ctx[i],
+			       clk_base + SCLK_BURST_POLICY + (i * 4));
+	}
+
+	writel_relaxed(sys_clk_divisor_ctx, clk_base + SYS_CLK_DIV);
+	writel_relaxed(system_rate_ctx, clk_base + SYSTEM_CLK_RATE);
+	writel_relaxed(spare_ctx, clk_base + SPARE_REG0);
+	writel_relaxed(misc_clk_enb_ctx, clk_base + MISC_CLK_ENB);
+	writel_relaxed(clk_arm_ctx, clk_base + CLK_MASK_ARM);
+}
+
 struct clk ** __init tegra_clk_init(void __iomem *regs, int num, int banks)
 {
 	clk_base = regs;
diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
index 581deb4f3ac0..5ba4f503aea0 100644
--- a/drivers/clk/tegra/clk.h
+++ b/drivers/clk/tegra/clk.h
@@ -10,6 +10,16 @@
 #include <linux/clkdev.h>
 #include <linux/delay.h>
 
+#define SCLK_BURST_POLICY	0x28
+#define SYSTEM_CLK_RATE		0x30
+#define CLK_MASK_ARM		0x44
+#define MISC_CLK_ENB		0x48
+#define CCLKG_BURST_POLICY	0x368
+#define CCLKLP_BURST_POLICY	0x370
+#define SYS_CLK_DIV		0x400
+#define SPARE_REG0		0x55c
+#define BURST_POLICY_REG_SIZE	2
+
 /**
  * struct tegra_clk_sync_source - external clock source from codec
  *
@@ -839,6 +849,10 @@ 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_sync_state_pll(struct clk_hw *hw);
+void tegra_cclkg_burst_policy_save_context(void);
+void tegra_cclkg_burst_policy_restore_context(void);
+void tegra_sclk_cclklp_burst_policy_save_context(void);
+void tegra_sclk_cpulp_burst_policy_restore_context(void);
 
 /* Combined read fence with delay */
 #define fence_udelay(delay, reg)	\
-- 
2.7.4