[PATCH V4 10/18] clk: tegra: add save and restore context support for peripheral clocks

[Sowjanya Komatineni]

This patch implements save and restore context for peripheral fixed
clock ops, peripheral gate clock ops, sdmmc mux clock ops, and
peripheral clock ops.

During system suspend, core power goes off and looses the settings
of the Tegra CAR controller registers.

So during suspend entry clock and reset state of peripherals is saved
and on resume they are restored to have clocks back to same rate and
state as before suspend.

Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
---
 drivers/clk/tegra/clk-periph-fixed.c | 31 ++++++++++++++++++++++++++
 drivers/clk/tegra/clk-periph-gate.c  | 34 ++++++++++++++++++++++++++++
 drivers/clk/tegra/clk-periph.c       | 43 ++++++++++++++++++++++++++++++++++++
 drivers/clk/tegra/clk-sdmmc-mux.c    | 30 +++++++++++++++++++++++++
 drivers/clk/tegra/clk.h              |  8 +++++++
 5 files changed, 146 insertions(+)

diff --git a/drivers/clk/tegra/clk-periph-fixed.c b/drivers/clk/tegra/clk-periph-fixed.c
index c088e7a280df..981f68b0a937 100644
--- a/drivers/clk/tegra/clk-periph-fixed.c
+++ b/drivers/clk/tegra/clk-periph-fixed.c
@@ -60,11 +60,42 @@ tegra_clk_periph_fixed_recalc_rate(struct clk_hw *hw,
 	return (unsigned long)rate;
 }
 
+static int tegra_clk_periph_fixed_save_context(struct clk_hw *hw)
+{
+	struct tegra_clk_periph_fixed *fixed = to_tegra_clk_periph_fixed(hw);
+	u32 mask = 1 << (fixed->num % 32);
+
+	fixed->enb_ctx = readl(fixed->base + fixed->regs->enb_reg) & mask;
+	fixed->rst_ctx = readl(fixed->base + fixed->regs->rst_reg) & mask;
+
+	return 0;
+}
+
+static void tegra_clk_periph_fixed_restore_context(struct clk_hw *hw)
+{
+	struct tegra_clk_periph_fixed *fixed = to_tegra_clk_periph_fixed(hw);
+	u32 mask = 1 << (fixed->num % 32);
+
+	if (fixed->enb_ctx)
+		tegra_clk_periph_fixed_enable(hw);
+	else
+		tegra_clk_periph_fixed_disable(hw);
+
+	udelay(2);
+
+	if (!fixed->rst_ctx) {
+		udelay(5); /* reset propogation delay */
+		writel(mask, fixed->base + fixed->regs->rst_reg);
+	}
+}
+
 static const struct clk_ops tegra_clk_periph_fixed_ops = {
 	.is_enabled = tegra_clk_periph_fixed_is_enabled,
 	.enable = tegra_clk_periph_fixed_enable,
 	.disable = tegra_clk_periph_fixed_disable,
 	.recalc_rate = tegra_clk_periph_fixed_recalc_rate,
+	.save_context = tegra_clk_periph_fixed_save_context,
+	.restore_context = tegra_clk_periph_fixed_restore_context,
 };
 
 struct clk *tegra_clk_register_periph_fixed(const char *name,
diff --git a/drivers/clk/tegra/clk-periph-gate.c b/drivers/clk/tegra/clk-periph-gate.c
index 4b31beefc9fc..6ba5b08e0787 100644
--- a/drivers/clk/tegra/clk-periph-gate.c
+++ b/drivers/clk/tegra/clk-periph-gate.c
@@ -25,6 +25,8 @@ static DEFINE_SPINLOCK(periph_ref_lock);
 
 #define read_rst(gate) \
 	readl_relaxed(gate->clk_base + (gate->regs->rst_reg))
+#define write_rst_set(val, gate) \
+	writel_relaxed(val, gate->clk_base + (gate->regs->rst_set_reg))
 #define write_rst_clr(val, gate) \
 	writel_relaxed(val, gate->clk_base + (gate->regs->rst_clr_reg))
 
@@ -110,10 +112,42 @@ static void clk_periph_disable(struct clk_hw *hw)
 	spin_unlock_irqrestore(&periph_ref_lock, flags);
 }
 
+static int clk_periph_gate_save_context(struct clk_hw *hw)
+{
+	struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
+
+	gate->clk_state_ctx = read_enb(gate) & periph_clk_to_bit(gate);
+	gate->rst_state_ctx = read_rst(gate) & periph_clk_to_bit(gate);
+
+	return 0;
+}
+
+static void clk_periph_gate_restore_context(struct clk_hw *hw)
+{
+	struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
+
+	if (gate->clk_state_ctx)
+		write_enb_set(periph_clk_to_bit(gate), gate);
+	else
+		write_enb_clr(periph_clk_to_bit(gate), gate);
+
+	udelay(5);
+
+	if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
+	    !(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
+		if (gate->rst_state_ctx)
+			write_rst_set(periph_clk_to_bit(gate), gate);
+		else
+			write_rst_clr(periph_clk_to_bit(gate), gate);
+	}
+}
+
 const struct clk_ops tegra_clk_periph_gate_ops = {
 	.is_enabled = clk_periph_is_enabled,
 	.enable = clk_periph_enable,
 	.disable = clk_periph_disable,
+	.save_context = clk_periph_gate_save_context,
+	.restore_context = clk_periph_gate_restore_context,
 };
 
 struct clk *tegra_clk_register_periph_gate(const char *name,
diff --git a/drivers/clk/tegra/clk-periph.c b/drivers/clk/tegra/clk-periph.c
index 58437da25156..d07882656e66 100644
--- a/drivers/clk/tegra/clk-periph.c
+++ b/drivers/clk/tegra/clk-periph.c
@@ -5,6 +5,7 @@
 
 #include <linux/clk-provider.h>
 #include <linux/export.h>
+#include <linux/io.h>
 #include <linux/slab.h>
 #include <linux/err.h>
 
@@ -99,6 +100,42 @@ static void clk_periph_disable(struct clk_hw *hw)
 	gate_ops->disable(gate_hw);
 }
 
+static int clk_periph_save_context(struct clk_hw *hw)
+{
+	struct tegra_clk_periph *periph = to_clk_periph(hw);
+	const struct clk_ops *gate_ops = periph->gate_ops;
+	struct clk_hw *gate_hw = &periph->gate.hw;
+	struct clk_hw *parent = clk_hw_get_parent(hw);
+	unsigned long parent_rate = clk_hw_get_rate(parent);
+
+	if (!(periph->gate.flags & TEGRA_PERIPH_NO_GATE))
+		gate_ops->save_context(gate_hw);
+
+	if (!(periph->gate.flags & TEGRA_PERIPH_NO_DIV))
+		periph->rate_ctx = clk_periph_recalc_rate(hw, parent_rate);
+
+	periph->parent_ctx = clk_periph_get_parent(hw);
+
+	return 0;
+}
+
+static void clk_periph_restore_context(struct clk_hw *hw)
+{
+	struct tegra_clk_periph *periph = to_clk_periph(hw);
+	const struct clk_ops *gate_ops = periph->gate_ops;
+	struct clk_hw *gate_hw = &periph->gate.hw;
+	struct clk_hw *parent = clk_hw_get_parent(hw);
+	unsigned long parent_rate = clk_hw_get_rate(parent);
+
+	if (!(periph->gate.flags & TEGRA_PERIPH_NO_GATE))
+		gate_ops->restore_context(gate_hw);
+
+	clk_periph_set_parent(hw, periph->parent_ctx);
+
+	if (!(periph->gate.flags & TEGRA_PERIPH_NO_DIV))
+		clk_periph_set_rate(hw, periph->rate_ctx, parent_rate);
+}
+
 const struct clk_ops tegra_clk_periph_ops = {
 	.get_parent = clk_periph_get_parent,
 	.set_parent = clk_periph_set_parent,
@@ -108,6 +145,8 @@ const struct clk_ops tegra_clk_periph_ops = {
 	.is_enabled = clk_periph_is_enabled,
 	.enable = clk_periph_enable,
 	.disable = clk_periph_disable,
+	.save_context = clk_periph_save_context,
+	.restore_context = clk_periph_restore_context,
 };
 
 static const struct clk_ops tegra_clk_periph_nodiv_ops = {
@@ -116,6 +155,8 @@ static const struct clk_ops tegra_clk_periph_nodiv_ops = {
 	.is_enabled = clk_periph_is_enabled,
 	.enable = clk_periph_enable,
 	.disable = clk_periph_disable,
+	.save_context = clk_periph_save_context,
+	.restore_context = clk_periph_restore_context,
 };
 
 static const struct clk_ops tegra_clk_periph_no_gate_ops = {
@@ -124,6 +165,8 @@ static const struct clk_ops tegra_clk_periph_no_gate_ops = {
 	.recalc_rate = clk_periph_recalc_rate,
 	.round_rate = clk_periph_round_rate,
 	.set_rate = clk_periph_set_rate,
+	.save_context = clk_periph_save_context,
+	.restore_context = clk_periph_restore_context,
 };
 
 static struct clk *_tegra_clk_register_periph(const char *name,
diff --git a/drivers/clk/tegra/clk-sdmmc-mux.c b/drivers/clk/tegra/clk-sdmmc-mux.c
index a5cd3e31dbae..fffe08e02c10 100644
--- a/drivers/clk/tegra/clk-sdmmc-mux.c
+++ b/drivers/clk/tegra/clk-sdmmc-mux.c
@@ -194,6 +194,34 @@ static void clk_sdmmc_mux_disable(struct clk_hw *hw)
 	gate_ops->disable(gate_hw);
 }
 
+static int clk_sdmmc_mux_save_context(struct clk_hw *hw)
+{
+	struct tegra_sdmmc_mux *sdmmc_mux = to_clk_sdmmc_mux(hw);
+	const struct clk_ops *gate_ops = sdmmc_mux->gate_ops;
+	struct clk_hw *gate_hw = &sdmmc_mux->gate.hw;
+	struct clk_hw *parent = clk_hw_get_parent(hw);
+	unsigned long parent_rate = clk_hw_get_rate(parent);
+
+	sdmmc_mux->rate_ctx = clk_sdmmc_mux_recalc_rate(hw, parent_rate);
+	sdmmc_mux->parent_ctx = clk_sdmmc_mux_get_parent(hw);
+	gate_ops->save_context(gate_hw);
+
+	return 0;
+}
+
+static void clk_sdmmc_mux_restore_context(struct clk_hw *hw)
+{
+	struct tegra_sdmmc_mux *sdmmc_mux = to_clk_sdmmc_mux(hw);
+	const struct clk_ops *gate_ops = sdmmc_mux->gate_ops;
+	struct clk_hw *gate_hw = &sdmmc_mux->gate.hw;
+	struct clk_hw *parent = clk_hw_get_parent(hw);
+	unsigned long parent_rate = clk_hw_get_rate(parent);
+
+	clk_sdmmc_mux_set_parent(hw, sdmmc_mux->parent_ctx);
+	clk_sdmmc_mux_set_rate(hw, sdmmc_mux->rate_ctx, parent_rate);
+	gate_ops->restore_context(gate_hw);
+}
+
 static const struct clk_ops tegra_clk_sdmmc_mux_ops = {
 	.get_parent = clk_sdmmc_mux_get_parent,
 	.set_parent = clk_sdmmc_mux_set_parent,
@@ -203,6 +231,8 @@ static const struct clk_ops tegra_clk_sdmmc_mux_ops = {
 	.is_enabled = clk_sdmmc_mux_is_enabled,
 	.enable = clk_sdmmc_mux_enable,
 	.disable = clk_sdmmc_mux_disable,
+	.save_context = clk_sdmmc_mux_save_context,
+	.restore_context = clk_sdmmc_mux_restore_context,
 };
 
 struct clk *tegra_clk_register_sdmmc_mux_div(const char *name,
diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
index 5a08827078e4..7b99496fefb9 100644
--- a/drivers/clk/tegra/clk.h
+++ b/drivers/clk/tegra/clk.h
@@ -523,6 +523,8 @@ struct tegra_clk_periph_gate {
 	int			clk_num;
 	int			*enable_refcnt;
 	const struct tegra_clk_periph_regs *regs;
+	bool			clk_state_ctx;
+	bool			rst_state_ctx;
 };
 
 #define to_clk_periph_gate(_hw)					\
@@ -549,6 +551,8 @@ struct tegra_clk_periph_fixed {
 	unsigned int mul;
 	unsigned int div;
 	unsigned int num;
+	bool enb_ctx;
+	bool rst_ctx;
 };
 
 struct clk *tegra_clk_register_periph_fixed(const char *name,
@@ -581,6 +585,8 @@ struct tegra_clk_periph {
 	const struct clk_ops	*mux_ops;
 	const struct clk_ops	*div_ops;
 	const struct clk_ops	*gate_ops;
+	unsigned long		rate_ctx;
+	u8			parent_ctx;
 };
 
 #define to_clk_periph(_hw) container_of(_hw, struct tegra_clk_periph, hw)
@@ -732,6 +738,8 @@ struct tegra_sdmmc_mux {
 	const struct clk_ops	*gate_ops;
 	struct tegra_clk_periph_gate	gate;
 	u8			div_flags;
+	unsigned long		rate_ctx;
+	u8			parent_ctx;
 };
 
 #define to_clk_sdmmc_mux(_hw) container_of(_hw, struct tegra_sdmmc_mux, hw)
-- 
2.7.4