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, 39 insertions, 0 deletions

diff --git a/drivers/clk/at91/clk-pll.c b/drivers/clk/at91/clk-pll.c
index 6ed986d3eee0..249d6a53cedf 100644
--- a/drivers/clk/at91/clk-pll.c
+++ b/drivers/clk/at91/clk-pll.c
@@ -40,6 +40,7 @@ struct clk_pll {
 	u16 mul;
 	const struct clk_pll_layout *layout;
 	const struct clk_pll_characteristics *characteristics;
+	struct at91_clk_pms pms;
 };
 
 static inline bool clk_pll_ready(struct regmap *regmap, int id)
@@ -260,6 +261,42 @@ static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 	return 0;
 }
 
+static int clk_pll_save_context(struct clk_hw *hw)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	struct clk_hw *parent_hw = clk_hw_get_parent(hw);
+
+	pll->pms.parent_rate = clk_hw_get_rate(parent_hw);
+	pll->pms.rate = clk_pll_recalc_rate(&pll->hw, pll->pms.parent_rate);
+	pll->pms.status = clk_pll_ready(pll->regmap, PLL_REG(pll->id));
+
+	return 0;
+}
+
+static void clk_pll_restore_context(struct clk_hw *hw)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	unsigned long calc_rate;
+	unsigned int pllr, pllr_out, pllr_count;
+	u8 out = 0;
+
+	if (pll->characteristics->out)
+		out = pll->characteristics->out[pll->range];
+
+	regmap_read(pll->regmap, PLL_REG(pll->id), &pllr);
+
+	calc_rate = (pll->pms.parent_rate / PLL_DIV(pllr)) *
+		     (PLL_MUL(pllr, pll->layout) + 1);
+	pllr_count = (pllr >> PLL_COUNT_SHIFT) & PLL_MAX_COUNT;
+	pllr_out = (pllr >> PLL_OUT_SHIFT) & out;
+
+	if (pll->pms.rate != calc_rate ||
+	    pll->pms.status != clk_pll_ready(pll->regmap, PLL_REG(pll->id)) ||
+	    pllr_count != PLL_MAX_COUNT ||
+	    (out && pllr_out != out))
+		pr_warn("PLLAR was not configured properly by firmware\n");
+}
+
 static const struct clk_ops pll_ops = {
 	.prepare = clk_pll_prepare,
 	.unprepare = clk_pll_unprepare,
@@ -267,6 +304,8 @@ static const struct clk_ops pll_ops = {
 	.recalc_rate = clk_pll_recalc_rate,
 	.round_rate = clk_pll_round_rate,
 	.set_rate = clk_pll_set_rate,
+	.save_context = clk_pll_save_context,
+	.restore_context = clk_pll_restore_context,
 };
 
 struct clk_hw * __init