ARM: imx53: Set DDR pins to high impedance when in suspend to RAM.

In order to save power the DDR pins should be put into high
impedance when in suspend to RAM.

This requires manually requesting self refresh (rather than using the
automatic mode implemented by the CCM / ESDCTL), followed by
reconfiguring the IOMUXC.

Of course the code to do this cannot itself run from DDR so the
code is copied to and executed from internal memory.

In my tests using a custom i.MX53 board with LPDDR2 RAM
this reduced the suspend power consumption from 200mW to 60mW.

Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/mach-imx/Makefile

@@ -90,6 +90,7 @@ obj-$(CONFIG_SOC_IMX7D) += mach-imx7d.o
 ifeq ($(CONFIG_SUSPEND),y)
 AFLAGS_suspend-imx6.o :=-Wa,-march=armv7-a
 obj-$(CONFIG_SOC_IMX6) += suspend-imx6.o
+obj-$(CONFIG_SOC_IMX53) += suspend-imx53.o
 endif
 obj-$(CONFIG_SOC_IMX6) += pm-imx6.o
 

arch/arm/mach-imx/common.h

@@ -116,9 +116,13 @@ int imx_cpu_kill(unsigned int cpu);
 
 #ifdef CONFIG_SUSPEND
 void v7_cpu_resume(void);
+void imx53_suspend(void __iomem *ocram_vbase);
+extern const u32 imx53_suspend_sz;
 void imx6_suspend(void __iomem *ocram_vbase);
 #else
 static inline void v7_cpu_resume(void) {}
+static inline void imx53_suspend(void __iomem *ocram_vbase) {}
+static const u32 imx53_suspend_sz;
 static inline void imx6_suspend(void __iomem *ocram_vbase) {}
 #endif
 

arch/arm/mach-imx/pm-imx5.c

@@ -13,7 +13,14 @@
 #include <linux/io.h>
 #include <linux/err.h>
 #include <linux/export.h>
+
+#include <linux/genalloc.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+
 #include <asm/cacheflush.h>
+#include <asm/fncpy.h>
 #include <asm/system_misc.h>
 #include <asm/tlbflush.h>
 
@@ -49,10 +56,50 @@
  */
 #define IMX5_DEFAULT_CPU_IDLE_STATE WAIT_UNCLOCKED_POWER_OFF
 
+struct imx5_suspend_io_state {
+	u32	offset;
+	u32	clear;
+	u32	set;
+	u32	saved_value;
+};
+
 struct imx5_pm_data {
 	phys_addr_t ccm_addr;
 	phys_addr_t cortex_addr;
 	phys_addr_t gpc_addr;
+	phys_addr_t m4if_addr;
+	phys_addr_t iomuxc_addr;
+	void (*suspend_asm)(void __iomem *ocram_vbase);
+	const u32 *suspend_asm_sz;
+	const struct imx5_suspend_io_state *suspend_io_config;
+	int suspend_io_count;
+};
+
+static const struct imx5_suspend_io_state imx53_suspend_io_config[] = {
+#define MX53_DSE_HIGHZ_MASK (0x7 << 19)
+	{.offset = 0x584, .clear = MX53_DSE_HIGHZ_MASK}, /* DQM0 */
+	{.offset = 0x594, .clear = MX53_DSE_HIGHZ_MASK}, /* DQM1 */
+	{.offset = 0x560, .clear = MX53_DSE_HIGHZ_MASK}, /* DQM2 */
+	{.offset = 0x554, .clear = MX53_DSE_HIGHZ_MASK}, /* DQM3 */
+	{.offset = 0x574, .clear = MX53_DSE_HIGHZ_MASK}, /* CAS */
+	{.offset = 0x588, .clear = MX53_DSE_HIGHZ_MASK}, /* RAS */
+	{.offset = 0x578, .clear = MX53_DSE_HIGHZ_MASK}, /* SDCLK_0 */
+	{.offset = 0x570, .clear = MX53_DSE_HIGHZ_MASK}, /* SDCLK_1 */
+
+	{.offset = 0x580, .clear = MX53_DSE_HIGHZ_MASK}, /* SDODT0 */
+	{.offset = 0x564, .clear = MX53_DSE_HIGHZ_MASK}, /* SDODT1 */
+	{.offset = 0x57c, .clear = MX53_DSE_HIGHZ_MASK}, /* SDQS0 */
+	{.offset = 0x590, .clear = MX53_DSE_HIGHZ_MASK}, /* SDQS1 */
+	{.offset = 0x568, .clear = MX53_DSE_HIGHZ_MASK}, /* SDQS2 */
+	{.offset = 0x558, .clear = MX53_DSE_HIGHZ_MASK}, /* SDSQ3 */
+	{.offset = 0x6f0, .clear = MX53_DSE_HIGHZ_MASK}, /* GRP_ADDS */
+	{.offset = 0x718, .clear = MX53_DSE_HIGHZ_MASK}, /* GRP_BODS */
+	{.offset = 0x71c, .clear = MX53_DSE_HIGHZ_MASK}, /* GRP_B1DS */
+	{.offset = 0x728, .clear = MX53_DSE_HIGHZ_MASK}, /* GRP_B2DS */
+	{.offset = 0x72c, .clear = MX53_DSE_HIGHZ_MASK}, /* GRP_B3DS */
+
+	/* Controls the CKE signal which is required to leave self refresh */
+	{.offset = 0x720, .clear = MX53_DSE_HIGHZ_MASK, .set = 1 << 19}, /* CTLDS */
 };
 
 static const struct imx5_pm_data imx51_pm_data __initconst = {
@@ -65,11 +112,35 @@ static const struct imx5_pm_data imx53_pm_data __initconst = {
 	.ccm_addr = 0x53fd4000,
 	.cortex_addr = 0x63fa0000,
 	.gpc_addr = 0x53fd8000,
+	.m4if_addr = 0x63fd8000,
+	.iomuxc_addr = 0x53fa8000,
+	.suspend_asm = &imx53_suspend,
+	.suspend_asm_sz = &imx53_suspend_sz,
+	.suspend_io_config = imx53_suspend_io_config,
+	.suspend_io_count = ARRAY_SIZE(imx53_suspend_io_config),
 };
 
+#define MX5_MAX_SUSPEND_IOSTATE ARRAY_SIZE(imx53_suspend_io_config)
+
+/*
+ * This structure is for passing necessary data for low level ocram
+ * suspend code(arch/arm/mach-imx/suspend-imx53.S), if this struct
+ * definition is changed, the offset definition in that file
+ * must be also changed accordingly otherwise, the suspend to ocram
+ * function will be broken!
+ */
+struct imx5_cpu_suspend_info {
+	void __iomem	*m4if_base;
+	void __iomem	*iomuxc_base;
+	u32		io_count;
+	struct imx5_suspend_io_state io_state[MX5_MAX_SUSPEND_IOSTATE];
+} __aligned(8);
+
 static void __iomem *ccm_base;
 static void __iomem *cortex_base;
 static void __iomem *gpc_base;
+static void __iomem *suspend_ocram_base;
+static void (*imx5_suspend_in_ocram_fn)(void __iomem *ocram_vbase);
 
 /*
  * set cpu low power mode before WFI instruction. This function is called
@@ -159,8 +230,15 @@ static int mx5_suspend_enter(suspend_state_t state)
 		/*clear the EMPGC0/1 bits */
 		__raw_writel(0, gpc_base + MXC_SRPG_EMPGC0_SRPGCR);
 		__raw_writel(0, gpc_base + MXC_SRPG_EMPGC1_SRPGCR);
+
+		if (imx5_suspend_in_ocram_fn)
+			imx5_suspend_in_ocram_fn(suspend_ocram_base);
+		else
+			cpu_do_idle();
+
+	} else {
+		cpu_do_idle();
 	}
-	cpu_do_idle();
 
 	/* return registers to default idle state */
 	mx5_cpu_lp_set(IMX5_DEFAULT_CPU_IDLE_STATE);
@@ -192,6 +270,111 @@ static void imx5_pm_idle(void)
 	imx5_cpu_do_idle();
 }
 
+static int __init imx_suspend_alloc_ocram(
+				size_t size,
+				void __iomem **virt_out,
+				phys_addr_t *phys_out)
+{
+	struct device_node *node;
+	struct platform_device *pdev;
+	struct gen_pool *ocram_pool;
+	unsigned long ocram_base;
+	void __iomem *virt;
+	phys_addr_t phys;
+	int ret = 0;
+
+	/* Copied from imx6: TODO factorize */
+	node = of_find_compatible_node(NULL, NULL, "mmio-sram");
+	if (!node) {
+		pr_warn("%s: failed to find ocram node!\n", __func__);
+		return -ENODEV;
+	}
+
+	pdev = of_find_device_by_node(node);
+	if (!pdev) {
+		pr_warn("%s: failed to find ocram device!\n", __func__);
+		ret = -ENODEV;
+		goto put_node;
+	}
+
+	ocram_pool = dev_get_gen_pool(&pdev->dev);
+	if (!ocram_pool) {
+		pr_warn("%s: ocram pool unavailable!\n", __func__);
+		ret = -ENODEV;
+		goto put_node;
+	}
+
+	ocram_base = gen_pool_alloc(ocram_pool, size);
+	if (!ocram_base) {
+		pr_warn("%s: unable to alloc ocram!\n", __func__);
+		ret = -ENOMEM;
+		goto put_node;
+	}
+
+	phys = gen_pool_virt_to_phys(ocram_pool, ocram_base);
+	virt = __arm_ioremap_exec(phys, size, false);
+	if (phys_out)
+		*phys_out = phys;
+	if (virt_out)
+		*virt_out = virt;
+
+put_node:
+	of_node_put(node);
+
+	return ret;
+}
+
+static int __init imx5_suspend_init(const struct imx5_pm_data *soc_data)
+{
+	struct imx5_cpu_suspend_info *suspend_info;
+	int ret;
+	/* Need this to avoid compile error due to const typeof in fncpy.h */
+	void (*suspend_asm)(void __iomem *) = soc_data->suspend_asm;
+
+	if (!suspend_asm)
+		return 0;
+
+	if (!soc_data->suspend_asm_sz || !*soc_data->suspend_asm_sz)
+		return -EINVAL;
+
+	ret = imx_suspend_alloc_ocram(
+		*soc_data->suspend_asm_sz + sizeof(*suspend_info),
+		&suspend_ocram_base, NULL);
+	if (ret)
+		return ret;
+
+	suspend_info = suspend_ocram_base;
+
+	suspend_info->io_count = soc_data->suspend_io_count;
+	memcpy(suspend_info->io_state, soc_data->suspend_io_config,
+	       sizeof(*suspend_info->io_state) * soc_data->suspend_io_count);
+
+	suspend_info->m4if_base = ioremap(soc_data->m4if_addr, SZ_16K);
+	if (!suspend_info->m4if_base) {
+		ret = -ENOMEM;
+		goto failed_map_m4if;
+	}
+
+	suspend_info->iomuxc_base = ioremap(soc_data->iomuxc_addr, SZ_16K);
+	if (!suspend_info->iomuxc_base) {
+		ret = -ENOMEM;
+		goto failed_map_iomuxc;
+	}
+
+	imx5_suspend_in_ocram_fn = fncpy(
+		suspend_ocram_base + sizeof(*suspend_info),
+		suspend_asm,
+		*soc_data->suspend_asm_sz);
+
+	return 0;
+
+failed_map_iomuxc:
+	iounmap(suspend_info->m4if_base);
+
+failed_map_m4if:
+	return ret;
+}
+
 static int __init imx5_pm_common_init(const struct imx5_pm_data *data)
 {
 	int ret;
@@ -218,6 +401,11 @@ static int __init imx5_pm_common_init(const struct imx5_pm_data *data)
 	if (ret)
 		pr_warn("%s: cpuidle init failed %d\n", __func__, ret);
 
+	ret = imx5_suspend_init(data);
+	if (ret)
+		pr_warn("%s: No DDR LPM support with suspend %d!\n",
+			__func__, ret);
+
 	suspend_set_ops(&mx5_suspend_ops);
 
 	return 0;