[PATCH v3 0/3] AT91 PM improvements

[PATCH v3 0/3] AT91 PM improvements

[Claudiu Beznea]

Hi,

This series adds ULP0 fast mode intended to reduce the suspend/resume
time in the detriment of power consumption (patch 1/3).
Along with this patch 2/3 adds code to avoid requesting a PM mode
not available on platforms not supporting it.
Patch 3/3 decrements a device_node refcount after its usage.

Thank you,
Claudiu Beznea

Changes in v3:
- force STANDBY and ULP0 modes for rm9200 and at91sam9 to avoid
  looping over all available modes and thus preserving booting time
- keep static in "static const int modes[] __initconst" in *_pm_init()
  functions to avoid compilation error "error: section attribute cannot
  be specified for local variables const int modes[] __initconst = {"
- remove sama5_pm() introduced in v2

Changes in v2:
- in patch 2/3:
	- move per SoC supported mode arrays in *_pm_init() functions.
	- use 2 booleans in at91_pm_modes_validate() for modes validation
	- continue to use array of supported modes in at91rm9200_pm_init()
	  and at91sam9_pm_init() instead of forcing
	  soc_pm.data.standby_mode = AT91_PM_STANDBY and
	  soc_pm.data.suspend_mode = AT91_PM_ULP0 to breaking the user
	  configuration (it might request ulp0 as standby mode or vice versa)

Claudiu Beznea (3):
  ARM: at91: pm: add support for ULP0 fast wakeup
  ARM: at91: pm: add per soc validation of pm modes
  ARM: at91: pm: of_node_put() after its usage

 arch/arm/mach-at91/pm.c         | 90 ++++++++++++++++++++++++++++++++++++++---
 arch/arm/mach-at91/pm.h         |  5 ++-
 arch/arm/mach-at91/pm_suspend.S | 41 +++++++++++++++++--
 3 files changed, 125 insertions(+), 11 deletions(-)

-- 
2.7.4

[PATCH v3 1/3] ARM: at91: pm: add support for ULP0 fast wakeup

[Claudiu Beznea]

ULP0 fast improves suspend/resume time with few milliseconds the drawback
being the power consumption. The mean values measured for suspend/resume
time are as follows (measured on SAMA5D2 Xplained board), ULP0 compared
with fast ULP0:
- ulp0 fast: suspend time: 169 ms, resume time: 216 ms
- ulp0     : suspend time: 197 ms, resume time: 258 ms

Current consumption while suspended (measured on SAMA5D2 Xplained board):
- ulp0 fast: 730uA
- ulp0     : 270uA

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 arch/arm/mach-at91/pm.c         |  9 +++++----
 arch/arm/mach-at91/pm.h         |  5 +++--
 arch/arm/mach-at91/pm_suspend.S | 41 +++++++++++++++++++++++++++++++++++++----
 3 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index 074bde64064e..04fdcbd57100 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -51,10 +51,11 @@ static struct at91_soc_pm soc_pm = {
 };
 
 static const match_table_t pm_modes __initconst = {
-	{ AT91_PM_STANDBY, "standby" },
-	{ AT91_PM_ULP0, "ulp0" },
-	{ AT91_PM_ULP1, "ulp1" },
-	{ AT91_PM_BACKUP, "backup" },
+	{ AT91_PM_STANDBY,	"standby" },
+	{ AT91_PM_ULP0,		"ulp0" },
+	{ AT91_PM_ULP0_FAST,    "ulp0-fast" },
+	{ AT91_PM_ULP1,		"ulp1" },
+	{ AT91_PM_BACKUP,	"backup" },
 	{ -1, NULL },
 };
 
diff --git a/arch/arm/mach-at91/pm.h b/arch/arm/mach-at91/pm.h
index 218e8d1a30fb..bfb260be371e 100644
--- a/arch/arm/mach-at91/pm.h
+++ b/arch/arm/mach-at91/pm.h
@@ -19,8 +19,9 @@
 
 #define	AT91_PM_STANDBY		0x00
 #define AT91_PM_ULP0		0x01
-#define AT91_PM_ULP1		0x02
-#define	AT91_PM_BACKUP		0x03
+#define AT91_PM_ULP0_FAST	0x02
+#define AT91_PM_ULP1		0x03
+#define	AT91_PM_BACKUP		0x04
 
 #ifndef __ASSEMBLY__
 struct at91_pm_data {
diff --git a/arch/arm/mach-at91/pm_suspend.S b/arch/arm/mach-at91/pm_suspend.S
index be9764e8d3fa..0184de05c1be 100644
--- a/arch/arm/mach-at91/pm_suspend.S
+++ b/arch/arm/mach-at91/pm_suspend.S
@@ -164,7 +164,22 @@ ENDPROC(at91_backup_mode)
 
 .macro at91_pm_ulp0_mode
 	ldr	pmc, .pmc_base
+	ldr	tmp2, .pm_mode
+	ldr	tmp3, .mckr_offset
+
+	/* Check if ULP0 fast variant has been requested. */
+	cmp	tmp2, #AT91_PM_ULP0_FAST
+	bne	0f
+
+	/* Set highest prescaler for power saving */
+	ldr	tmp1, [pmc, tmp3]
+	bic	tmp1, tmp1, #AT91_PMC_PRES
+	orr	tmp1, tmp1, #AT91_PMC_PRES_64
+	str	tmp1, [pmc, tmp3]
+	wait_mckrdy
+	b	1f
 
+0:
 	/* Turn off the crystal oscillator */
 	ldr	tmp1, [pmc, #AT91_CKGR_MOR]
 	bic	tmp1, tmp1, #AT91_PMC_MOSCEN
@@ -192,7 +207,18 @@ ENDPROC(at91_backup_mode)
 	/* Wait for interrupt */
 1:	at91_cpu_idle
 
-	/* Restore RC oscillator state */
+	/* Check if ULP0 fast variant has been requested. */
+	cmp	tmp2, #AT91_PM_ULP0_FAST
+	bne	5f
+
+	/* Set lowest prescaler for fast resume. */
+	ldr	tmp1, [pmc, tmp3]
+	bic	tmp1, tmp1, #AT91_PMC_PRES
+	str	tmp1, [pmc, tmp3]
+	wait_mckrdy
+	b	6f
+
+5:	/* Restore RC oscillator state */
 	ldr	tmp1, .saved_osc_status
 	tst	tmp1, #AT91_PMC_MOSCRCS
 	beq	4f
@@ -216,6 +242,7 @@ ENDPROC(at91_backup_mode)
 	str	tmp1, [pmc, #AT91_CKGR_MOR]
 
 	wait_moscrdy
+6:
 .endm
 
 /**
@@ -473,23 +500,29 @@ ENDPROC(at91_backup_mode)
 ENTRY(at91_ulp_mode)
 	ldr	pmc, .pmc_base
 	ldr	tmp2, .mckr_offset
+	ldr	tmp3, .pm_mode
 
 	/* Save Master clock setting */
 	ldr	tmp1, [pmc, tmp2]
 	str	tmp1, .saved_mckr
 
 	/*
-	 * Set the Master clock source to slow clock
+	 * Set master clock source to:
+	 * - MAINCK if using ULP0 fast variant
+	 * - slow clock, otherwise
 	 */
 	bic	tmp1, tmp1, #AT91_PMC_CSS
+	cmp	tmp3, #AT91_PM_ULP0_FAST
+	bne	save_mck
+	orr	tmp1, tmp1, #AT91_PMC_CSS_MAIN
+save_mck:
 	str	tmp1, [pmc, tmp2]
 
 	wait_mckrdy
 
 	at91_plla_disable
 
-	ldr	r0, .pm_mode
-	cmp	r0, #AT91_PM_ULP1
+	cmp	tmp3, #AT91_PM_ULP1
 	beq	ulp1_mode
 
 	at91_pm_ulp0_mode
-- 
2.7.4

[PATCH v3 2/3] ARM: at91: pm: add per soc validation of pm modes

[Claudiu Beznea]

Not all SoCs supports all the PM mode. User may end up settings,
e.g. backup mode, on a non SAMA5D2 device, but the mode to not be valid.
If backup mode is used on a devices not supporting it there will be no
way of resuming other than rebooting.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 arch/arm/mach-at91/pm.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index 04fdcbd57100..4aaab918f982 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -785,6 +785,51 @@ static const struct of_device_id atmel_pmc_ids[] __initconst = {
 	{ /* sentinel */ },
 };
 
+static void __init at91_pm_modes_validate(const int *modes, int len)
+{
+	u8 i, standby = 0, suspend = 0;
+	int mode;
+
+	for (i = 0; i < len; i++) {
+		if (standby && suspend)
+			break;
+
+		if (modes[i] == soc_pm.data.standby_mode && !standby) {
+			standby = 1;
+			continue;
+		}
+
+		if (modes[i] == soc_pm.data.suspend_mode && !suspend) {
+			suspend = 1;
+			continue;
+		}
+	}
+
+	if (!standby) {
+		if (soc_pm.data.suspend_mode == AT91_PM_STANDBY)
+			mode = AT91_PM_ULP0;
+		else
+			mode = AT91_PM_STANDBY;
+
+		pr_warn("AT91: PM: %s mode not supported! Using %s.\n",
+			pm_modes[soc_pm.data.standby_mode].pattern,
+			pm_modes[mode].pattern);
+		soc_pm.data.standby_mode = mode;
+	}
+
+	if (!suspend) {
+		if (soc_pm.data.standby_mode == AT91_PM_ULP0)
+			mode = AT91_PM_STANDBY;
+		else
+			mode = AT91_PM_ULP0;
+
+		pr_warn("AT91: PM: %s mode not supported! Using %s.\n",
+			pm_modes[soc_pm.data.suspend_mode].pattern,
+			pm_modes[mode].pattern);
+		soc_pm.data.suspend_mode = mode;
+	}
+}
+
 static void __init at91_pm_init(void (*pm_idle)(void))
 {
 	struct device_node *pmc_np;
@@ -826,6 +871,14 @@ void __init at91rm9200_pm_init(void)
 	if (!IS_ENABLED(CONFIG_SOC_AT91RM9200))
 		return;
 
+	/*
+	 * Force STANDBY and ULP0 mode to avoid calling
+	 * at91_pm_modes_validate() which may increase booting time.
+	 * Platform supports anyway only STANDBY and ULP0 modes.
+	 */
+	soc_pm.data.standby_mode = AT91_PM_STANDBY;
+	soc_pm.data.suspend_mode = AT91_PM_ULP0;
+
 	at91_dt_ramc();
 
 	/*
@@ -838,9 +891,14 @@ void __init at91rm9200_pm_init(void)
 
 void __init sam9x60_pm_init(void)
 {
+	static const int modes[] __initconst = {
+		AT91_PM_STANDBY, AT91_PM_ULP0, AT91_PM_ULP0_FAST, AT91_PM_ULP1,
+	};
+
 	if (!IS_ENABLED(CONFIG_SOC_SAM9X60))
 		return;
 
+	at91_pm_modes_validate(modes, ARRAY_SIZE(modes));
 	at91_pm_modes_init();
 	at91_dt_ramc();
 	at91_pm_init(at91sam9x60_idle);
@@ -854,26 +912,46 @@ void __init at91sam9_pm_init(void)
 	if (!IS_ENABLED(CONFIG_SOC_AT91SAM9))
 		return;
 
+	/*
+	 * Force STANDBY and ULP0 mode to avoid calling
+	 * at91_pm_modes_validate() which may increase booting time.
+	 * Platform supports anyway only STANDBY and ULP0 modes.
+	 */
+	soc_pm.data.standby_mode = AT91_PM_STANDBY;
+	soc_pm.data.suspend_mode = AT91_PM_ULP0;
+
 	at91_dt_ramc();
 	at91_pm_init(at91sam9_idle);
 }
 
 void __init sama5_pm_init(void)
 {
+	static const int modes[] __initconst = {
+		AT91_PM_STANDBY, AT91_PM_ULP0, AT91_PM_ULP0_FAST,
+	};
+
 	if (!IS_ENABLED(CONFIG_SOC_SAMA5))
 		return;
 
+	at91_pm_modes_validate(modes, ARRAY_SIZE(modes));
 	at91_dt_ramc();
 	at91_pm_init(NULL);
 }
 
 void __init sama5d2_pm_init(void)
 {
+	static const int modes[] __initconst = {
+		AT91_PM_STANDBY, AT91_PM_ULP0, AT91_PM_ULP0_FAST, AT91_PM_ULP1,
+		AT91_PM_BACKUP,
+	};
+
 	if (!IS_ENABLED(CONFIG_SOC_SAMA5D2))
 		return;
 
+	at91_pm_modes_validate(modes, ARRAY_SIZE(modes));
 	at91_pm_modes_init();
-	sama5_pm_init();
+	at91_dt_ramc();
+	at91_pm_init(NULL);
 
 	soc_pm.ws_ids = sama5d2_ws_ids;
 	soc_pm.config_shdwc_ws = at91_sama5d2_config_shdwc_ws;
-- 
2.7.4

[PATCH v3 3/3] ARM: at91: pm: of_node_put() after its usage

[Claudiu Beznea]

Put node after it has been used.

Fixes: 13f16017d3e3f ("ARM: at91: pm: Tie the USB clock mask to the pmc")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 arch/arm/mach-at91/pm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index 4aaab918f982..9f1101de80c6 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -841,6 +841,7 @@ static void __init at91_pm_init(void (*pm_idle)(void))
 
 	pmc_np = of_find_matching_node_and_match(NULL, atmel_pmc_ids, &of_id);
 	soc_pm.data.pmc = of_iomap(pmc_np, 0);
+	of_node_put(pmc_np);
 	if (!soc_pm.data.pmc) {
 		pr_err("AT91: PM not supported, PMC not found\n");
 		return;
-- 
2.7.4

Re: [PATCH v3 0/3] AT91 PM improvements

[Alexandre Belloni]

On Wed, 5 Aug 2020 11:36:47 +0300, Claudiu Beznea wrote:
> This series adds ULP0 fast mode intended to reduce the suspend/resume
> time in the detriment of power consumption (patch 1/3).
> Along with this patch 2/3 adds code to avoid requesting a PM mode
> not available on platforms not supporting it.
> Patch 3/3 decrements a device_node refcount after its usage.
> 
> Thank you,
> Claudiu Beznea
> 
> [...]

Applied, thanks!

[1/3] ARM: at91: pm: add support for ULP0 fast wakeup
      commit: e70bfc2fa8fe1a95a522f9d1ccf24d3d9b81366a
[2/3] ARM: at91: pm: add per soc validation of pm modes
      commit: 39add36049c347dffcb2be872dd442c137625f17
[3/3] ARM: at91: pm: of_node_put() after its usage
      commit: e222f943519564978e082c152b4140a47e93392c

Best regards,
-- 
Alexandre Belloni <alexandre.belloni@bootlin.com>