[PATCH v2 2/2] ARM: kirkwood: Add basic suspend-to-RAM support

[Ezequiel Garcia]

Implements suspend-to-RAM support in a standby-like fashion:
when the SoC enters suspend state the memory PM units are disabled,
the DDR is set in self-refresh mode, and the CPU is set in WFI.

Signed-off-by: Simon Guinot <sguinot at lacie.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia at free-electrons.com>
---
Changes from v1:

  * Removed clock gating. Each peripheral is in charge of implementing
    a proper suspend/resume path, including gateable clock handling.

 arch/arm/mach-kirkwood/Makefile                   |  1 +
 arch/arm/mach-kirkwood/include/mach/bridge-regs.h |  2 +
 arch/arm/mach-kirkwood/pm.c                       | 69 +++++++++++++++++++++++
 3 files changed, 72 insertions(+)
 create mode 100644 arch/arm/mach-kirkwood/pm.c

diff --git a/arch/arm/mach-kirkwood/Makefile b/arch/arm/mach-kirkwood/Makefile
index 937d4e1..788db9c 100644
--- a/arch/arm/mach-kirkwood/Makefile
+++ b/arch/arm/mach-kirkwood/Makefile
@@ -1,4 +1,5 @@
 obj-y				+= common.o pcie.o
+obj-$(CONFIG_PM)		+= pm.o
 obj-$(CONFIG_KIRKWOOD_LEGACY)	+= irq.o mpp.o
 obj-$(CONFIG_MACH_D2NET_V2)		+= d2net_v2-setup.o lacie_v2-common.o
 obj-$(CONFIG_MACH_NET2BIG_V2)		+= netxbig_v2-setup.o lacie_v2-common.o
diff --git a/arch/arm/mach-kirkwood/include/mach/bridge-regs.h b/arch/arm/mach-kirkwood/include/mach/bridge-regs.h
index 91242c9..8b9d1c9 100644
--- a/arch/arm/mach-kirkwood/include/mach/bridge-regs.h
+++ b/arch/arm/mach-kirkwood/include/mach/bridge-regs.h
@@ -78,4 +78,6 @@
 #define CGC_TDM			(1 << 20)
 #define CGC_RESERVED		(0x6 << 21)
 
+#define MEMORY_PM_CTRL		(BRIDGE_VIRT_BASE + 0x118)
+
 #endif
diff --git a/arch/arm/mach-kirkwood/pm.c b/arch/arm/mach-kirkwood/pm.c
new file mode 100644
index 0000000..364734c
--- /dev/null
+++ b/arch/arm/mach-kirkwood/pm.c
@@ -0,0 +1,69 @@
+/*
+ * Power Management driver for Marvell Kirkwood SoCs
+ *
+ * Copyright (C) 2013 Ezequiel Garcia <ezequiel at vanguardiasur.com.ar>
+ * Copyright (C) 2010 Simon Guinot <sguinot at lacie.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License,
+ * version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/suspend.h>
+#include <linux/io.h>
+#include <mach/bridge-regs.h>
+
+static void __iomem *ddr_operation_base;
+
+static void kirkwood_suspend_mem(void)
+{
+	u32 mem_pm_ctrl;
+
+	mem_pm_ctrl = readl(MEMORY_PM_CTRL);
+
+	/* Set peripherals to low-power mode */
+	writel_relaxed(~0, MEMORY_PM_CTRL);
+
+	/* Set DDR in self-refresh */
+	writel_relaxed(0x7, ddr_operation_base);
+
+	/*
+	 * Set CPU in wait-for-interrupt state.
+	 * This disables the CPU core clocks,
+	 * the array clocks, and also the L2 controller.
+	 */
+	cpu_do_idle();
+
+	writel_relaxed(mem_pm_ctrl, MEMORY_PM_CTRL);
+}
+
+static int kirkwood_suspend_enter(suspend_state_t state)
+{
+	switch (state) {
+	case PM_SUSPEND_MEM:
+		kirkwood_suspend_mem();
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static const struct platform_suspend_ops kirkwood_suspend_ops = {
+	.enter = kirkwood_suspend_enter,
+	.valid = suspend_valid_only_mem,
+};
+
+static int __init kirkwood_pm_init(void)
+{
+	ddr_operation_base = ioremap(DDR_OPERATION_BASE, 4);
+	suspend_set_ops(&kirkwood_suspend_ops);
+	return 0;
+}
+arch_initcall(kirkwood_pm_init);
-- 
1.8.1.5