ARM: at91: pm: Add sama5d2 backup mode

The sama5d2 has a mode were it is possible to cut power to the SoC while
keeping the RAM in self refresh.
Resuming from that mode needs support in the firmware/bootloader.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Wenyou Yang <wenyou.yang@atmel.com>

arch/arm/mach-at91/generic.h

@@ -15,10 +15,12 @@
 extern void __init at91rm9200_pm_init(void);
 extern void __init at91sam9_pm_init(void);
 extern void __init sama5_pm_init(void);
+extern void __init sama5d2_pm_init(void);
 #else
 static inline void __init at91rm9200_pm_init(void) { }
 static inline void __init at91sam9_pm_init(void) { }
 static inline void __init sama5_pm_init(void) { }
+static inline void __init sama5d2_pm_init(void) { }
 #endif
 
 #endif /* _AT91_GENERIC_H */

arch/arm/mach-at91/pm.c

@@ -22,6 +22,7 @@
 #include <asm/cacheflush.h>
 #include <asm/fncpy.h>
 #include <asm/system_misc.h>
+#include <asm/suspend.h>
 
 #include "generic.h"
 #include "pm.h"
@@ -58,6 +59,14 @@ static int at91_pm_valid_state(suspend_state_t state)
 	}
 }
 
+static int canary = 0xA5A5A5A5;
+
+static struct at91_pm_bu {
+	int suspended;
+	unsigned long reserved;
+	phys_addr_t canary;
+	phys_addr_t resume;
+} *pm_bu;
 
 static suspend_state_t target_state;
 
@@ -123,15 +132,39 @@ static void (*at91_suspend_sram_fn)(struct at91_pm_data *);
 extern void at91_pm_suspend_in_sram(struct at91_pm_data *pm_data);
 extern u32 at91_pm_suspend_in_sram_sz;
 
-static void at91_pm_suspend(suspend_state_t state)
+static int at91_suspend_finish(unsigned long val)
 {
-	pm_data.mode = (state == PM_SUSPEND_MEM) ? AT91_PM_SLOW_CLOCK : 0;
-
 	flush_cache_all();
 	outer_disable();
 
 	at91_suspend_sram_fn(&pm_data);
 
+	return 0;
+}
+
+static void at91_pm_suspend(suspend_state_t state)
+{
+	if (pm_data.deepest_state == AT91_PM_BACKUP)
+		if (state == PM_SUSPEND_MEM)
+			pm_data.mode = AT91_PM_BACKUP;
+		else
+			pm_data.mode = AT91_PM_SLOW_CLOCK;
+	else
+		pm_data.mode = (state == PM_SUSPEND_MEM) ? AT91_PM_SLOW_CLOCK : 0;
+
+	if (pm_data.mode == AT91_PM_BACKUP) {
+		pm_bu->suspended = 1;
+
+		cpu_suspend(0, at91_suspend_finish);
+
+		/* The SRAM is lost between suspend cycles */
+		at91_suspend_sram_fn = fncpy(at91_suspend_sram_fn,
+					     &at91_pm_suspend_in_sram,
+					     at91_pm_suspend_in_sram_sz);
+	} else {
+		at91_suspend_finish(0);
+	}
+
 	outer_resume();
 }
 
@@ -436,6 +469,70 @@ static void __init at91_pm_sram_init(void)
 			&at91_pm_suspend_in_sram, at91_pm_suspend_in_sram_sz);
 }
 
+static void __init at91_pm_backup_init(void)
+{
+	struct gen_pool *sram_pool;
+	struct device_node *np;
+	struct platform_device *pdev = NULL;
+
+	pm_bu = NULL;
+
+	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d2-shdwc");
+	if (!np) {
+		pr_warn("%s: failed to find shdwc!\n", __func__);
+		return;
+	}
+
+	pm_data.shdwc = of_iomap(np, 0);
+	of_node_put(np);
+
+	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d2-sfrbu");
+	if (!np) {
+		pr_warn("%s: failed to find sfrbu!\n", __func__);
+		goto sfrbu_fail;
+	}
+
+	pm_data.sfrbu = of_iomap(np, 0);
+	of_node_put(np);
+	pm_bu = NULL;
+
+	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d2-securam");
+	if (!np)
+		goto securam_fail;
+
+	pdev = of_find_device_by_node(np);
+	of_node_put(np);
+	if (!pdev) {
+		pr_warn("%s: failed to find securam device!\n", __func__);
+		goto securam_fail;
+	}
+
+	sram_pool = gen_pool_get(&pdev->dev, NULL);
+	if (!sram_pool) {
+		pr_warn("%s: securam pool unavailable!\n", __func__);
+		goto securam_fail;
+	}
+
+	pm_bu = (void *)gen_pool_alloc(sram_pool, sizeof(struct at91_pm_bu));
+	if (!pm_bu) {
+		pr_warn("%s: unable to alloc securam!\n", __func__);
+		goto securam_fail;
+	}
+
+	pm_bu->suspended = 0;
+	pm_bu->canary = virt_to_phys(&canary);
+	pm_bu->resume = virt_to_phys(cpu_resume);
+
+	return;
+
+sfrbu_fail:
+	iounmap(pm_data.shdwc);
+	pm_data.shdwc = NULL;
+securam_fail:
+	iounmap(pm_data.sfrbu);
+	pm_data.sfrbu = NULL;
+}
+
 struct pmc_info {
 	unsigned long uhp_udp_mask;
 };
@@ -510,3 +607,9 @@ void __init sama5_pm_init(void)
 	at91_dt_ramc();
 	at91_pm_init(NULL);
 }
+
+void __init sama5d2_pm_init(void)
+{
+	at91_pm_backup_init();
+	sama5_pm_init();
+}

arch/arm/mach-at91/pm.h

@@ -22,6 +22,7 @@
 #define AT91_MEMCTRL_DDRSDR	2
 
 #define	AT91_PM_SLOW_CLOCK	0x01
+#define	AT91_PM_BACKUP		0x02
 
 #ifndef __ASSEMBLY__
 struct at91_pm_data {
@@ -30,6 +31,9 @@ struct at91_pm_data {
 	unsigned long uhp_udp_mask;
 	unsigned int memctrl;
 	unsigned int mode;
+	void __iomem *shdwc;
+	void __iomem *sfrbu;
+	unsigned int deepest_state;
 };
 #endif
 

arch/arm/mach-at91/pm_data-offsets.c

@@ -9,5 +9,8 @@ int main(void)
 	DEFINE(PM_DATA_RAMC1,		offsetof(struct at91_pm_data, ramc[1]));
 	DEFINE(PM_DATA_MEMCTRL,	offsetof(struct at91_pm_data, memctrl));
 	DEFINE(PM_DATA_MODE,		offsetof(struct at91_pm_data, mode));
+	DEFINE(PM_DATA_SHDWC,		offsetof(struct at91_pm_data, shdwc));
+	DEFINE(PM_DATA_SFRBU,		offsetof(struct at91_pm_data, sfrbu));
+
 	return 0;
 }

arch/arm/mach-at91/pm_suspend.S

@@ -97,15 +97,61 @@ ENTRY(at91_pm_suspend_in_sram)
 	str	tmp1, .memtype
 	ldr	tmp1, [r0, #PM_DATA_MODE]
 	str	tmp1, .pm_mode
+	/* Both ldrne below are here to preload their address in the TLB */
+	ldr	tmp1, [r0, #PM_DATA_SHDWC]
+	str	tmp1, .shdwc
+	cmp	tmp1, #0
+	ldrne	tmp2, [tmp1, #0]
+	ldr	tmp1, [r0, #PM_DATA_SFRBU]
+	str	tmp1, .sfr
+	cmp	tmp1, #0
+	ldrne	tmp2, [tmp1, #0x10]
 
 	/* Active the self-refresh mode */
 	mov	r0, #SRAMC_SELF_FRESH_ACTIVE
 	bl	at91_sramc_self_refresh
 
 	ldr	r0, .pm_mode
-	tst	r0, #AT91_PM_SLOW_CLOCK
-	beq	skip_disable_main_clock
+	cmp	r0, #AT91_PM_SLOW_CLOCK
+	beq	slow_clock
+	cmp	r0, #AT91_PM_BACKUP
+	beq	backup_mode
 
+	/* Wait for interrupt */
+	ldr	pmc, .pmc_base
+	at91_cpu_idle
+	b	exit_suspend
+
+slow_clock:
+	bl	at91_slowck_mode
+	b	exit_suspend
+backup_mode:
+	bl	at91_backup_mode
+	b	exit_suspend
+
+exit_suspend:
+	/* Exit the self-refresh mode */
+	mov	r0, #SRAMC_SELF_FRESH_EXIT
+	bl	at91_sramc_self_refresh
+
+	/* Restore registers, and return */
+	ldmfd	sp!, {r4 - r12, pc}
+ENDPROC(at91_pm_suspend_in_sram)
+
+ENTRY(at91_backup_mode)
+	/*BUMEN*/
+	ldr	r0, .sfr
+	mov	tmp1, #0x1
+	str	tmp1, [r0, #0x10]
+
+	/* Shutdown */
+	ldr	r0, .shdwc
+	mov	tmp1, #0xA5000000
+	add	tmp1, tmp1, #0x1
+	str	tmp1, [r0, #0]
+ENDPROC(at91_backup_mode)
+
+ENTRY(at91_slowck_mode)
 	ldr	pmc, .pmc_base
 
 	/* Save Master clock setting */
@@ -134,18 +180,9 @@ ENTRY(at91_pm_suspend_in_sram)
 	orr	tmp1, tmp1, #AT91_PMC_KEY
 	str	tmp1, [pmc, #AT91_CKGR_MOR]
 
-skip_disable_main_clock:
-	ldr	pmc, .pmc_base
-
 	/* Wait for interrupt */
 	at91_cpu_idle
 
-	ldr	r0, .pm_mode
-	tst	r0, #AT91_PM_SLOW_CLOCK
-	beq	skip_enable_main_clock
-
-	ldr	pmc, .pmc_base
-
 	/* Turn on the main oscillator */
 	ldr	tmp1, [pmc, #AT91_CKGR_MOR]
 	orr	tmp1, tmp1, #AT91_PMC_MOSCEN
@@ -174,14 +211,8 @@ skip_disable_main_clock:
 
 	wait_mckrdy
 
-skip_enable_main_clock:
-	/* Exit the self-refresh mode */
-	mov	r0, #SRAMC_SELF_FRESH_EXIT
-	bl	at91_sramc_self_refresh
-
-	/* Restore registers, and return */
-	ldmfd	sp!, {r4 - r12, pc}
-ENDPROC(at91_pm_suspend_in_sram)
+	mov	pc, lr
+ENDPROC(at91_slowck_mode)
 
 /*
  * void at91_sramc_self_refresh(unsigned int is_active)
@@ -314,6 +345,10 @@ ENDPROC(at91_sramc_self_refresh)
 	.word 0
 .sramc1_base:
 	.word 0
+.shdwc:
+	.word 0
+.sfr:
+	.word 0
 .memtype:
 	.word 0
 .pm_mode:

arch/arm/mach-at91/sama5.c

@@ -34,7 +34,6 @@ DT_MACHINE_START(sama5_dt, "Atmel SAMA5")
 MACHINE_END
 
 static const char *const sama5_alt_dt_board_compat[] __initconst = {
-	"atmel,sama5d2",
 	"atmel,sama5d4",
 	NULL
 };
@@ -45,3 +44,21 @@ DT_MACHINE_START(sama5_alt_dt, "Atmel SAMA5")
 	.dt_compat	= sama5_alt_dt_board_compat,
 	.l2c_aux_mask	= ~0UL,
 MACHINE_END
+
+static void __init sama5d2_init(void)
+{
+	of_platform_default_populate(NULL, NULL, NULL);
+	sama5d2_pm_init();
+}
+
+static const char *const sama5d2_compat[] __initconst = {
+	"atmel,sama5d2",
+	NULL
+};
+
+DT_MACHINE_START(sama5d2, "Atmel SAMA5")
+	/* Maintainer: Atmel */
+	.init_machine	= sama5d2_init,
+	.dt_compat	= sama5d2_compat,
+	.l2c_aux_mask	= ~0UL,
+MACHINE_END