[PATCH v5 0/3] Clock patches for SAMA5D2 backup mode

[PATCH v5 0/3] Clock patches for SAMA5D2 backup mode

[Romain Izard]

While the core of the backup mode for SAMA5D2 has been integrated in
v4.13, it is far from complete. Individual controllers in the chip have
drivers that do not support the reset of the registers during suspend,
and they need to be adapted to handle it.

The first patch uses the clock wakeup code from the prototype backup
mode instead of the version integrated in the mainline, as the mainline
version is not stable. During a test loop with two-second backup
suspend, the mainline version will hang in less than one day, whereas
the prototype version has been running the same test for more than a
week without hanging.

Changes in v2:
* drop the IIO patch duplicating existing code
* determine the number of programmable clocks to save dynamically
* declare a required local variable in the tty/serial patch

Changes in v3:
* drop dev_printk changes for PMECC
* rework the resume code for PMECC
* improve comments on PMC clock handling

Changes in v4:
* fix a bug in the PMECC resume code

Changes in v5:
* drop all patches already taken
* split the patch series by subsystem

Romain Izard (8):
  clk: at91: pmc: Wait for clocks when resuming
  clk: at91: pmc: Save SCSR during suspend
  clk: at91: pmc: Support backup for programmable clocks

 drivers/clk/at91/clk-programmable.c |  2 ++
 drivers/clk/at91/pmc.c              | 63 +++++++++++++++++++++++++++++++------
 drivers/clk/at91/pmc.h              |  2 ++
 3 files changed, 57 insertions(+), 10 deletions(-)

-- 
2.11.0

[PATCH v5 1/3] clk: at91: pmc: Wait for clocks when resuming

[Romain Izard]

Wait for the syncronization of all clocks when resuming, not only the
UPLL clock. Do not use regmap_read_poll_timeout, as it will call BUG()
when interrupts are masked, which is the case in here.

Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
---
 drivers/clk/at91/pmc.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
index 775af473fe11..5c2b26de303e 100644
--- a/drivers/clk/at91/pmc.c
+++ b/drivers/clk/at91/pmc.c
@@ -107,10 +107,20 @@ static int pmc_suspend(void)
 	return 0;
 }
 
+static bool pmc_ready(unsigned int mask)
+{
+	unsigned int status;
+
+	regmap_read(pmcreg, AT91_PMC_SR, &status);
+
+	return ((status & mask) == mask) ? 1 : 0;
+}
+
 static void pmc_resume(void)
 {
-	int i, ret = 0;
+	int i;
 	u32 tmp;
+	u32 mask = AT91_PMC_MCKRDY | AT91_PMC_LOCKA;
 
 	regmap_read(pmcreg, AT91_PMC_MCKR, &tmp);
 	if (pmc_cache.mckr != tmp)
@@ -134,13 +144,11 @@ static void pmc_resume(void)
 			     AT91_PMC_PCR_CMD);
 	}
 
-	if (pmc_cache.uckr & AT91_PMC_UPLLEN) {
-		ret = regmap_read_poll_timeout(pmcreg, AT91_PMC_SR, tmp,
-					       !(tmp & AT91_PMC_LOCKU),
-					       10, 5000);
-		if (ret)
-			pr_crit("USB PLL didn't lock when resuming\n");
-	}
+	if (pmc_cache.uckr & AT91_PMC_UPLLEN)
+		mask |= AT91_PMC_LOCKU;
+
+	while (!pmc_ready(mask))
+		cpu_relax();
 }
 
 static struct syscore_ops pmc_syscore_ops = {
-- 
2.11.0

[PATCH v5 2/3] clk: at91: pmc: Save SCSR during suspend

[Romain Izard]

The contents of the System Clock Status Register (SCSR) needs to be
restored into the System Clock Enable Register (SCER).

As the bootloader will restore some clocks by itself, the issue can be
missed as only the USB controller, the LCD controller, the Image Sensor
controller and the programmable clocks will be impacted.

Fix the obvious typo in the suspend/resume code, as the IMR register
does not need to be saved twice.

Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
---
 drivers/clk/at91/pmc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
index 5c2b26de303e..07dc2861ad3f 100644
--- a/drivers/clk/at91/pmc.c
+++ b/drivers/clk/at91/pmc.c
@@ -86,7 +86,7 @@ static int pmc_suspend(void)
 {
 	int i;
 
-	regmap_read(pmcreg, AT91_PMC_IMR, &pmc_cache.scsr);
+	regmap_read(pmcreg, AT91_PMC_SCSR, &pmc_cache.scsr);
 	regmap_read(pmcreg, AT91_PMC_PCSR, &pmc_cache.pcsr0);
 	regmap_read(pmcreg, AT91_CKGR_UCKR, &pmc_cache.uckr);
 	regmap_read(pmcreg, AT91_CKGR_MOR, &pmc_cache.mor);
@@ -129,7 +129,7 @@ static void pmc_resume(void)
 	if (pmc_cache.pllar != tmp)
 		pr_warn("PLLAR was not configured properly by the firmware\n");
 
-	regmap_write(pmcreg, AT91_PMC_IMR, pmc_cache.scsr);
+	regmap_write(pmcreg, AT91_PMC_SCER, pmc_cache.scsr);
 	regmap_write(pmcreg, AT91_PMC_PCER, pmc_cache.pcsr0);
 	regmap_write(pmcreg, AT91_CKGR_UCKR, pmc_cache.uckr);
 	regmap_write(pmcreg, AT91_CKGR_MOR, pmc_cache.mor);
-- 
2.11.0

[PATCH v5 3/3] clk: at91: pmc: Support backup for programmable clocks

[Romain Izard]

From: Romain Izard <romain.izard@mobile-devices.fr>

When an AT91 programmable clock is declared in the device tree, register
it into the Power Management Controller driver. On entering suspend mode,
the driver saves and restores the Programmable Clock registers to support
the backup mode for these clocks.

Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
---
Changes in v2:
* register PCKs on clock startup

Changes in v3:
* improve comments on hanling 0 in pmc_register_id and pmc_register_pck
* declare local variables earlier for checkpatch

 drivers/clk/at91/clk-programmable.c |  2 ++
 drivers/clk/at91/pmc.c              | 35 +++++++++++++++++++++++++++++++++++
 drivers/clk/at91/pmc.h              |  2 ++
 3 files changed, 39 insertions(+)

diff --git a/drivers/clk/at91/clk-programmable.c b/drivers/clk/at91/clk-programmable.c
index 85a449cf61e3..0e6aab1252fc 100644
--- a/drivers/clk/at91/clk-programmable.c
+++ b/drivers/clk/at91/clk-programmable.c
@@ -204,6 +204,8 @@ at91_clk_register_programmable(struct regmap *regmap,
 	if (ret) {
 		kfree(prog);
 		hw = ERR_PTR(ret);
+	} else {
+		pmc_register_pck(id);
 	}
 
 	return hw;
diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
index 07dc2861ad3f..1fa27f4ea538 100644
--- a/drivers/clk/at91/pmc.c
+++ b/drivers/clk/at91/pmc.c
@@ -22,6 +22,7 @@
 #include "pmc.h"
 
 #define PMC_MAX_IDS 128
+#define PMC_MAX_PCKS 8
 
 int of_at91_get_clk_range(struct device_node *np, const char *propname,
 			  struct clk_range *range)
@@ -50,6 +51,7 @@ EXPORT_SYMBOL_GPL(of_at91_get_clk_range);
 static struct regmap *pmcreg;
 
 static u8 registered_ids[PMC_MAX_IDS];
+static u8 registered_pcks[PMC_MAX_PCKS];
 
 static struct
 {
@@ -66,8 +68,13 @@ static struct
 	u32 pcr[PMC_MAX_IDS];
 	u32 audio_pll0;
 	u32 audio_pll1;
+	u32 pckr[PMC_MAX_PCKS];
 } pmc_cache;
 
+/*
+ * As Peripheral ID 0 is invalid on AT91 chips, the identifier is stored
+ * without alteration in the table, and 0 is for unused clocks.
+ */
 void pmc_register_id(u8 id)
 {
 	int i;
@@ -82,9 +89,28 @@ void pmc_register_id(u8 id)
 	}
 }
 
+/*
+ * As Programmable Clock 0 is valid on AT91 chips, there is an offset
+ * of 1 between the stored value and the real clock ID.
+ */
+void pmc_register_pck(u8 pck)
+{
+	int i;
+
+	for (i = 0; i < PMC_MAX_PCKS; i++) {
+		if (registered_pcks[i] == 0) {
+			registered_pcks[i] = pck + 1;
+			break;
+		}
+		if (registered_pcks[i] == (pck + 1))
+			break;
+	}
+}
+
 static int pmc_suspend(void)
 {
 	int i;
+	u8 num;
 
 	regmap_read(pmcreg, AT91_PMC_SCSR, &pmc_cache.scsr);
 	regmap_read(pmcreg, AT91_PMC_PCSR, &pmc_cache.pcsr0);
@@ -103,6 +129,10 @@ static int pmc_suspend(void)
 		regmap_read(pmcreg, AT91_PMC_PCR,
 			    &pmc_cache.pcr[registered_ids[i]]);
 	}
+	for (i = 0; registered_pcks[i]; i++) {
+		num = registered_pcks[i] - 1;
+		regmap_read(pmcreg, AT91_PMC_PCKR(num), &pmc_cache.pckr[num]);
+	}
 
 	return 0;
 }
@@ -119,6 +149,7 @@ static bool pmc_ready(unsigned int mask)
 static void pmc_resume(void)
 {
 	int i;
+	u8 num;
 	u32 tmp;
 	u32 mask = AT91_PMC_MCKRDY | AT91_PMC_LOCKA;
 
@@ -143,6 +174,10 @@ static void pmc_resume(void)
 			     pmc_cache.pcr[registered_ids[i]] |
 			     AT91_PMC_PCR_CMD);
 	}
+	for (i = 0; registered_pcks[i]; i++) {
+		num = registered_pcks[i] - 1;
+		regmap_write(pmcreg, AT91_PMC_PCKR(num), pmc_cache.pckr[num]);
+	}
 
 	if (pmc_cache.uckr & AT91_PMC_UPLLEN)
 		mask |= AT91_PMC_LOCKU;
diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
index 858e8ef7e8db..d22b1fa9ecdc 100644
--- a/drivers/clk/at91/pmc.h
+++ b/drivers/clk/at91/pmc.h
@@ -31,8 +31,10 @@ int of_at91_get_clk_range(struct device_node *np, const char *propname,
 
 #ifdef CONFIG_PM
 void pmc_register_id(u8 id);
+void pmc_register_pck(u8 pck);
 #else
 static inline void pmc_register_id(u8 id) {}
+static inline void pmc_register_pck(u8 pck) {}
 #endif
 
 #endif /* __PMC_H_ */
-- 
2.11.0