power: reset: at91-poweroff: timely shutdown LPDDR memories

commit 0b040874 upstream.

LPDDR memories can only handle up to 400 uncontrolled power off. Ensure the
proper power off sequence is used before shutting down the platform.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/power/reset/Kconfig

@@ -32,7 +32,7 @@ config POWER_RESET_AT91_RESET
 
 config POWER_RESET_AT91_SAMA5D2_SHDWC
 	tristate "Atmel AT91 SAMA5D2-Compatible shutdown controller driver"
-	depends on ARCH_AT91 || COMPILE_TEST
+	depends on ARCH_AT91
 	default SOC_SAMA5
 	help
 	  This driver supports the alternate shutdown controller for some Atmel

drivers/power/reset/at91-poweroff.c

@@ -14,9 +14,12 @@
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/printk.h>
 
+#include <soc/at91/at91sam9_ddrsdr.h>
+
 #define AT91_SHDW_CR	0x00		/* Shut Down Control Register */
 #define AT91_SHDW_SHDW		BIT(0)			/* Shut Down command */
 #define AT91_SHDW_KEY		(0xa5 << 24)		/* KEY Password */
@@ -50,6 +53,7 @@ static const char *shdwc_wakeup_modes[] = {
 
 static void __iomem *at91_shdwc_base;
 static struct clk *sclk;
+static void __iomem *mpddrc_base;
 
 static void __init at91_wakeup_status(void)
 {
@@ -73,6 +77,29 @@ static void at91_poweroff(void)
 	writel(AT91_SHDW_KEY | AT91_SHDW_SHDW, at91_shdwc_base + AT91_SHDW_CR);
 }
 
+static void at91_lpddr_poweroff(void)
+{
+	asm volatile(
+		/* Align to cache lines */
+		".balign 32\n\t"
+
+		/* Ensure AT91_SHDW_CR is in the TLB by reading it */
+		"	ldr	r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
+
+		/* Power down SDRAM0 */
+		"	str	%1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
+		/* Shutdown CPU */
+		"	str	%3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
+
+		"	b	.\n\t"
+		:
+		: "r" (mpddrc_base),
+		  "r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
+		  "r" (at91_shdwc_base),
+		  "r" cpu_to_le32(AT91_SHDW_KEY | AT91_SHDW_SHDW)
+		: "r0");
+}
+
 static int at91_poweroff_get_wakeup_mode(struct device_node *np)
 {
 	const char *pm;
@@ -124,6 +151,8 @@ static void at91_poweroff_dt_set_wakeup_mode(struct platform_device *pdev)
 static int __init at91_poweroff_probe(struct platform_device *pdev)
 {
 	struct resource *res;
+	struct device_node *np;
+	u32 ddr_type;
 	int ret;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -150,12 +179,30 @@ static int __init at91_poweroff_probe(struct platform_device *pdev)
 
 	pm_power_off = at91_poweroff;
 
+	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d3-ddramc");
+	if (!np)
+		return 0;
+
+	mpddrc_base = of_iomap(np, 0);
+	of_node_put(np);
+
+	if (!mpddrc_base)
+		return 0;
+
+	ddr_type = readl(mpddrc_base + AT91_DDRSDRC_MDR) & AT91_DDRSDRC_MD;
+	if ((ddr_type == AT91_DDRSDRC_MD_LPDDR2) ||
+	    (ddr_type == AT91_DDRSDRC_MD_LPDDR3))
+		pm_power_off = at91_lpddr_poweroff;
+	else
+		iounmap(mpddrc_base);
+
 	return 0;
 }
 
 static int __exit at91_poweroff_remove(struct platform_device *pdev)
 {
-	if (pm_power_off == at91_poweroff)
+	if (pm_power_off == at91_poweroff ||
+	    pm_power_off == at91_lpddr_poweroff)
 		pm_power_off = NULL;
 
 	clk_disable_unprepare(sclk);
@@ -163,6 +210,11 @@ static int __exit at91_poweroff_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id at91_ramc_of_match[] = {
+	{ .compatible = "atmel,sama5d3-ddramc", },
+	{ /* sentinel */ }
+};
+
 static const struct of_device_id at91_poweroff_of_match[] = {
 	{ .compatible = "atmel,at91sam9260-shdwc", },
 	{ .compatible = "atmel,at91sam9rl-shdwc", },

drivers/power/reset/at91-sama5d2_shdwc.c

@@ -22,9 +22,12 @@
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/printk.h>
 
+#include <soc/at91/at91sam9_ddrsdr.h>
+
 #define SLOW_CLOCK_FREQ	32768
 
 #define AT91_SHDW_CR	0x00		/* Shut Down Control Register */
@@ -75,6 +78,7 @@ struct shdwc {
  */
 static struct shdwc *at91_shdwc;
 static struct clk *sclk;
+static void __iomem *mpddrc_base;
 
 static const unsigned long long sdwc_dbc_period[] = {
 	0, 3, 32, 512, 4096, 32768,
@@ -108,6 +112,29 @@ static void at91_poweroff(void)
 	       at91_shdwc->at91_shdwc_base + AT91_SHDW_CR);
 }
 
+static void at91_lpddr_poweroff(void)
+{
+	asm volatile(
+		/* Align to cache lines */
+		".balign 32\n\t"
+
+		/* Ensure AT91_SHDW_CR is in the TLB by reading it */
+		"	ldr	r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
+
+		/* Power down SDRAM0 */
+		"	str	%1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
+		/* Shutdown CPU */
+		"	str	%3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
+
+		"	b	.\n\t"
+		:
+		: "r" (mpddrc_base),
+		  "r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
+		  "r" (at91_shdwc->at91_shdwc_base),
+		  "r" cpu_to_le32(AT91_SHDW_KEY | AT91_SHDW_SHDW)
+		: "r0");
+}
+
 static u32 at91_shdwc_debouncer_value(struct platform_device *pdev,
 				      u32 in_period_us)
 {
@@ -212,6 +239,8 @@ static int __init at91_shdwc_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	const struct of_device_id *match;
+	struct device_node *np;
+	u32 ddr_type;
 	int ret;
 
 	if (!pdev->dev.of_node)
@@ -249,6 +278,23 @@ static int __init at91_shdwc_probe(struct platform_device *pdev)
 
 	pm_power_off = at91_poweroff;
 
+	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d3-ddramc");
+	if (!np)
+		return 0;
+
+	mpddrc_base = of_iomap(np, 0);
+	of_node_put(np);
+
+	if (!mpddrc_base)
+		return 0;
+
+	ddr_type = readl(mpddrc_base + AT91_DDRSDRC_MDR) & AT91_DDRSDRC_MD;
+	if ((ddr_type == AT91_DDRSDRC_MD_LPDDR2) ||
+	    (ddr_type == AT91_DDRSDRC_MD_LPDDR3))
+		pm_power_off = at91_lpddr_poweroff;
+	else
+		iounmap(mpddrc_base);
+
 	return 0;
 }
 
@@ -256,7 +302,8 @@ static int __exit at91_shdwc_remove(struct platform_device *pdev)
 {
 	struct shdwc *shdw = platform_get_drvdata(pdev);
 
-	if (pm_power_off == at91_poweroff)
+	if (pm_power_off == at91_poweroff ||
+	    pm_power_off == at91_lpddr_poweroff)
 		pm_power_off = NULL;
 
 	/* Reset values to disable wake-up features  */