clk: at91: re-factor clocks suspend/resume

SAMA5D2 and SAMA7G5 have a special power saving mode (backup mode) where
most of the SoC's components are powered off (including PMC). Resuming
from this mode is done with the help of bootloader. Peripherals are not
aware of the power saving mode thus most of them are disabling clocks in
proper suspend API and re-enable them in resume API without taking into
account the previously setup rate. Moreover some of the peripherals are
acting as wakeup sources and are not disabling the clocks in this
scenario, when suspending. Since backup mode cuts the power for
peripherals, in resume part these clocks needs to be re-configured.

The initial PMC suspend/resume code was designed only for SAMA5D2's PMC
(as it was the only one supporting backup mode). SAMA7G supports also
backup mode and its PMC is different (few new functionalities, different
registers offsets, different offsets in registers for each
functionalities). To address both SAMA5D2 and SAMA7G5 PMC add
.save_context()/.resume_context() support to each clocks driver and call
this from PMC driver.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-2-claudiu.beznea@microchip.com
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

1 files changed, 182 insertions, 12 deletions

diff --git a/drivers/clk/at91/clk-master.c b/drivers/clk/at91/clk-master.c
index a80427980bf7..f75549fff023 100644
--- a/drivers/clk/at91/clk-master.c
+++ b/drivers/clk/at91/clk-master.c
@@ -37,6 +37,7 @@ struct clk_master {
 	spinlock_t *lock;
 	const struct clk_master_layout *layout;
 	const struct clk_master_characteristics *characteristics;
+	struct at91_clk_pms pms;
 	u32 *mux_table;
 	u32 mckr;
 	int chg_pid;
@@ -112,10 +113,52 @@ static unsigned long clk_master_div_recalc_rate(struct clk_hw *hw,
 	return rate;
 }
 
+static int clk_master_div_save_context(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	struct clk_hw *parent_hw = clk_hw_get_parent(hw);
+	unsigned long flags;
+	unsigned int mckr, div;
+
+	spin_lock_irqsave(master->lock, flags);
+	regmap_read(master->regmap, master->layout->offset, &mckr);
+	spin_unlock_irqrestore(master->lock, flags);
+
+	mckr &= master->layout->mask;
+	div = (mckr >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK;
+	div = master->characteristics->divisors[div];
+
+	master->pms.parent_rate = clk_hw_get_rate(parent_hw);
+	master->pms.rate = DIV_ROUND_CLOSEST(master->pms.parent_rate, div);
+
+	return 0;
+}
+
+static void clk_master_div_restore_context(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	unsigned long flags;
+	unsigned int mckr;
+	u8 div;
+
+	spin_lock_irqsave(master->lock, flags);
+	regmap_read(master->regmap, master->layout->offset, &mckr);
+	spin_unlock_irqrestore(master->lock, flags);
+
+	mckr &= master->layout->mask;
+	div = (mckr >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK;
+	div = master->characteristics->divisors[div];
+
+	if (div != DIV_ROUND_CLOSEST(master->pms.parent_rate, master->pms.rate))
+		pr_warn("MCKR DIV not configured properly by firmware!\n");
+}
+
 static const struct clk_ops master_div_ops = {
 	.prepare = clk_master_prepare,
 	.is_prepared = clk_master_is_prepared,
 	.recalc_rate = clk_master_div_recalc_rate,
+	.save_context = clk_master_div_save_context,
+	.restore_context = clk_master_div_restore_context,
 };
 
 static int clk_master_div_set_rate(struct clk_hw *hw, unsigned long rate,
@@ -125,7 +168,9 @@ static int clk_master_div_set_rate(struct clk_hw *hw, unsigned long rate,
 	const struct clk_master_characteristics *characteristics =
 						master->characteristics;
 	unsigned long flags;
+	unsigned int mckr, tmp;
 	int div, i;
+	int ret;
 
 	div = DIV_ROUND_CLOSEST(parent_rate, rate);
 	if (div > ARRAY_SIZE(characteristics->divisors))
@@ -145,11 +190,24 @@ static int clk_master_div_set_rate(struct clk_hw *hw, unsigned long rate,
 		return -EINVAL;
 
 	spin_lock_irqsave(master->lock, flags);
-	regmap_update_bits(master->regmap, master->layout->offset,
-			   (MASTER_DIV_MASK << MASTER_DIV_SHIFT),
-			   (div << MASTER_DIV_SHIFT));
+	ret = regmap_read(master->regmap, master->layout->offset, &mckr);
+	if (ret)
+		goto unlock;
+
+	tmp = mckr & master->layout->mask;
+	tmp = (tmp >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK;
+	if (tmp == div)
+		goto unlock;
+
+	mckr &= ~(MASTER_DIV_MASK << MASTER_DIV_SHIFT);
+	mckr |= (div << MASTER_DIV_SHIFT);
+	ret = regmap_write(master->regmap, master->layout->offset, mckr);
+	if (ret)
+		goto unlock;
+
 	while (!clk_master_ready(master))
 		cpu_relax();
+unlock:
 	spin_unlock_irqrestore(master->lock, flags);
 
 	return 0;
@@ -197,12 +255,25 @@ static int clk_master_div_determine_rate(struct clk_hw *hw,
 	return 0;
 }
 
+static void clk_master_div_restore_context_chg(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	int ret;
+
+	ret = clk_master_div_set_rate(hw, master->pms.rate,
+				      master->pms.parent_rate);
+	if (ret)
+		pr_warn("Failed to restore MCK DIV clock\n");
+}
+
 static const struct clk_ops master_div_ops_chg = {
 	.prepare = clk_master_prepare,
 	.is_prepared = clk_master_is_prepared,
 	.recalc_rate = clk_master_div_recalc_rate,
 	.determine_rate = clk_master_div_determine_rate,
 	.set_rate = clk_master_div_set_rate,
+	.save_context = clk_master_div_save_context,
+	.restore_context = clk_master_div_restore_context_chg,
 };
 
 static void clk_sama7g5_master_best_diff(struct clk_rate_request *req,
@@ -272,7 +343,8 @@ static int clk_master_pres_set_rate(struct clk_hw *hw, unsigned long rate,
 {
 	struct clk_master *master = to_clk_master(hw);
 	unsigned long flags;
-	unsigned int pres;
+	unsigned int pres, mckr, tmp;
+	int ret;
 
 	pres = DIV_ROUND_CLOSEST(parent_rate, rate);
 	if (pres > MASTER_PRES_MAX)
@@ -284,15 +356,27 @@ static int clk_master_pres_set_rate(struct clk_hw *hw, unsigned long rate,
 		pres = ffs(pres) - 1;
 
 	spin_lock_irqsave(master->lock, flags);
-	regmap_update_bits(master->regmap, master->layout->offset,
-			   (MASTER_PRES_MASK << master->layout->pres_shift),
-			   (pres << master->layout->pres_shift));
+	ret = regmap_read(master->regmap, master->layout->offset, &mckr);
+	if (ret)
+		goto unlock;
+
+	mckr &= master->layout->mask;
+	tmp = (mckr >> master->layout->pres_shift) & MASTER_PRES_MASK;
+	if (pres == tmp)
+		goto unlock;
+
+	mckr &= ~(MASTER_PRES_MASK << master->layout->pres_shift);
+	mckr |= (pres << master->layout->pres_shift);
+	ret = regmap_write(master->regmap, master->layout->offset, mckr);
+	if (ret)
+		goto unlock;
 
 	while (!clk_master_ready(master))
 		cpu_relax();
+unlock:
 	spin_unlock_irqrestore(master->lock, flags);
 
-	return 0;
+	return ret;
 }
 
 static unsigned long clk_master_pres_recalc_rate(struct clk_hw *hw,
@@ -330,11 +414,68 @@ static u8 clk_master_pres_get_parent(struct clk_hw *hw)
 	return mckr & AT91_PMC_CSS;
 }
 
+static int clk_master_pres_save_context(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	struct clk_hw *parent_hw = clk_hw_get_parent(hw);
+	unsigned long flags;
+	unsigned int val, pres;
+
+	spin_lock_irqsave(master->lock, flags);
+	regmap_read(master->regmap, master->layout->offset, &val);
+	spin_unlock_irqrestore(master->lock, flags);
+
+	val &= master->layout->mask;
+	pres = (val >> master->layout->pres_shift) & MASTER_PRES_MASK;
+	if (pres == MASTER_PRES_MAX && master->characteristics->have_div3_pres)
+		pres = 3;
+	else
+		pres = (1 << pres);
+
+	master->pms.parent = val & AT91_PMC_CSS;
+	master->pms.parent_rate = clk_hw_get_rate(parent_hw);
+	master->pms.rate = DIV_ROUND_CLOSEST_ULL(master->pms.parent_rate, pres);
+
+	return 0;
+}
+
+static void clk_master_pres_restore_context(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	unsigned long flags;
+	unsigned int val, pres;
+
+	spin_lock_irqsave(master->lock, flags);
+	regmap_read(master->regmap, master->layout->offset, &val);
+	spin_unlock_irqrestore(master->lock, flags);
+
+	val &= master->layout->mask;
+	pres = (val >> master->layout->pres_shift) & MASTER_PRES_MASK;
+	if (pres == MASTER_PRES_MAX && master->characteristics->have_div3_pres)
+		pres = 3;
+	else
+		pres = (1 << pres);
+
+	if (master->pms.rate !=
+	    DIV_ROUND_CLOSEST_ULL(master->pms.parent_rate, pres) ||
+	    (master->pms.parent != (val & AT91_PMC_CSS)))
+		pr_warn("MCKR PRES was not configured properly by firmware!\n");
+}
+
+static void clk_master_pres_restore_context_chg(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+
+	clk_master_pres_set_rate(hw, master->pms.rate, master->pms.parent_rate);
+}
+
 static const struct clk_ops master_pres_ops = {
 	.prepare = clk_master_prepare,
 	.is_prepared = clk_master_is_prepared,
 	.recalc_rate = clk_master_pres_recalc_rate,
 	.get_parent = clk_master_pres_get_parent,
+	.save_context = clk_master_pres_save_context,
+	.restore_context = clk_master_pres_restore_context,
 };
 
 static const struct clk_ops master_pres_ops_chg = {
@@ -344,6 +485,8 @@ static const struct clk_ops master_pres_ops_chg = {
 	.recalc_rate = clk_master_pres_recalc_rate,
 	.get_parent = clk_master_pres_get_parent,
 	.set_rate = clk_master_pres_set_rate,
+	.save_context = clk_master_pres_save_context,
+	.restore_context = clk_master_pres_restore_context_chg,
 };
 
 static struct clk_hw * __init
@@ -539,20 +682,21 @@ static int clk_sama7g5_master_set_parent(struct clk_hw *hw, u8 index)
 	return 0;
 }
 
-static int clk_sama7g5_master_enable(struct clk_hw *hw)
+static void clk_sama7g5_master_set(struct clk_master *master,
+				   unsigned int status)
 {
-	struct clk_master *master = to_clk_master(hw);
 	unsigned long flags;
 	unsigned int val, cparent;
+	unsigned int enable = status ? PMC_MCR_EN : 0;
 
 	spin_lock_irqsave(master->lock, flags);
 
 	regmap_write(master->regmap, PMC_MCR, PMC_MCR_ID(master->id));
 	regmap_read(master->regmap, PMC_MCR, &val);
 	regmap_update_bits(master->regmap, PMC_MCR,
-			   PMC_MCR_EN | PMC_MCR_CSS | PMC_MCR_DIV |
+			   enable | PMC_MCR_CSS | PMC_MCR_DIV |
 			   PMC_MCR_CMD | PMC_MCR_ID_MSK,
-			   PMC_MCR_EN | (master->parent << PMC_MCR_CSS_SHIFT) |
+			   enable | (master->parent << PMC_MCR_CSS_SHIFT) |
 			   (master->div << MASTER_DIV_SHIFT) |
 			   PMC_MCR_CMD | PMC_MCR_ID(master->id));
 
@@ -563,6 +707,13 @@ static int clk_sama7g5_master_enable(struct clk_hw *hw)
 		cpu_relax();
 
 	spin_unlock_irqrestore(master->lock, flags);
+}
+
+static int clk_sama7g5_master_enable(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+
+	clk_sama7g5_master_set(master, 1);
 
 	return 0;
 }
@@ -620,6 +771,23 @@ static int clk_sama7g5_master_set_rate(struct clk_hw *hw, unsigned long rate,
 	return 0;
 }
 
+static int clk_sama7g5_master_save_context(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+
+	master->pms.status = clk_sama7g5_master_is_enabled(hw);
+
+	return 0;
+}
+
+static void clk_sama7g5_master_restore_context(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+
+	if (master->pms.status)
+		clk_sama7g5_master_set(master, master->pms.status);
+}
+
 static const struct clk_ops sama7g5_master_ops = {
 	.enable = clk_sama7g5_master_enable,
 	.disable = clk_sama7g5_master_disable,
@@ -629,6 +797,8 @@ static const struct clk_ops sama7g5_master_ops = {
 	.set_rate = clk_sama7g5_master_set_rate,
 	.get_parent = clk_sama7g5_master_get_parent,
 	.set_parent = clk_sama7g5_master_set_parent,
+	.save_context = clk_sama7g5_master_save_context,
+	.restore_context = clk_sama7g5_master_restore_context,
 };
 
 struct clk_hw * __init