ARM: mvebu: implement suspend/resume support for Armada XP

This commit implements the core of the platform code to enable
suspend/resume on Armada XP. It registers the platform_suspend_ops
structure, and implements the ->enter() hook of this structure.

It is worth mentioning that this commit only provides the SoC-level
part of suspend/resume, which calls into some board-specific code
provided in a follow-up commit.

The most important thing that this SoC-level code has to do is to
build an in-memory structure that contains a magic number, the return
address in the kernel after resume, and a set of address/value
pairs. This structure is used by the bootloader to restore a certain
number of registers (according to the set of address/value pairs) and
then jump back into the kernel at the provided location.

The code also puts the SDRAM into self-refresh mode, before calling
into board-specific code to actually enter the suspend to RAM state.

[ jac - add email exchange between Andrew Lunn and Thomas Petazzoni to better
describe who consumes the address/value pairs ]

> > Is this a well defined mechanism supported by mainline uboot, barebox
> > etc. Or is it some Marvell extension to their uboot?
>
> As far as I know, it is a Marvell extension to their "binary header",
> so it's done even before U-Boot starts. Since the hardware needs
> assistance from the bootloader to do suspend/resume, there is
> necessarily a certain amount of cooperation/agreement needed by what
> the kernel does and what the bootloader expects. I'm not sure there's
> any "standard" mechanism here. Do you know of any?
>
> I know the suspend/resume on the Blackfin architecture works the same
> way (at least it used to work that way years ago when I did a bit of
> Blackfin stuff). And here as well, there was some cooperation between
> the kernel and the bootloader. See
> arch/blackfin/mach-common/dpmc_modes.S, function do_hibernate() at the
> end.
>

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1416585613-2113-10-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

1 files changed, 218 insertions, 0 deletions

diff --git a/arch/arm/mach-mvebu/pm.c b/arch/arm/mach-mvebu/pm.c
new file mode 100644
index 000000000000..6573a8f11f70
--- /dev/null
+++ b/arch/arm/mach-mvebu/pm.c
@@ -0,0 +1,218 @@
+/*
+ * Suspend/resume support. Currently supporting Armada XP only.
+ *
+ * Copyright (C) 2014 Marvell
+ *
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/cpu_pm.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mbus.h>
+#include <linux/of_address.h>
+#include <linux/suspend.h>
+#include <asm/cacheflush.h>
+#include <asm/outercache.h>
+#include <asm/suspend.h>
+
+#include "coherency.h"
+#include "pmsu.h"
+
+#define SDRAM_CONFIG_OFFS                  0x0
+#define  SDRAM_CONFIG_SR_MODE_BIT          BIT(24)
+#define SDRAM_OPERATION_OFFS               0x18
+#define  SDRAM_OPERATION_SELF_REFRESH      0x7
+#define SDRAM_DLB_EVICTION_OFFS            0x30c
+#define  SDRAM_DLB_EVICTION_THRESHOLD_MASK 0xff
+
+static void (*mvebu_board_pm_enter)(void __iomem *sdram_reg, u32 srcmd);
+static void __iomem *sdram_ctrl;
+
+static int mvebu_pm_powerdown(unsigned long data)
+{
+	u32 reg, srcmd;
+
+	flush_cache_all();
+	outer_flush_all();
+
+	/*
+	 * Issue a Data Synchronization Barrier instruction to ensure
+	 * that all state saving has been completed.
+	 */
+	dsb();
+
+	/* Flush the DLB and wait ~7 usec */
+	reg = readl(sdram_ctrl + SDRAM_DLB_EVICTION_OFFS);
+	reg &= ~SDRAM_DLB_EVICTION_THRESHOLD_MASK;
+	writel(reg, sdram_ctrl + SDRAM_DLB_EVICTION_OFFS);
+
+	udelay(7);
+
+	/* Set DRAM in battery backup mode */
+	reg = readl(sdram_ctrl + SDRAM_CONFIG_OFFS);
+	reg &= ~SDRAM_CONFIG_SR_MODE_BIT;
+	writel(reg, sdram_ctrl + SDRAM_CONFIG_OFFS);
+
+	/* Prepare to go to self-refresh */
+
+	srcmd = readl(sdram_ctrl + SDRAM_OPERATION_OFFS);
+	srcmd &= ~0x1F;
+	srcmd |= SDRAM_OPERATION_SELF_REFRESH;
+
+	mvebu_board_pm_enter(sdram_ctrl + SDRAM_OPERATION_OFFS, srcmd);
+
+	return 0;
+}
+
+#define BOOT_INFO_ADDR      0x3000
+#define BOOT_MAGIC_WORD	    0xdeadb002
+#define BOOT_MAGIC_LIST_END 0xffffffff
+
+/*
+ * Those registers are accessed before switching the internal register
+ * base, which is why we hardcode the 0xd0000000 base address, the one
+ * used by the SoC out of reset.
+ */
+#define MBUS_WINDOW_12_CTRL       0xd00200b0
+#define MBUS_INTERNAL_REG_ADDRESS 0xd0020080
+
+#define SDRAM_WIN_BASE_REG(x)	(0x20180 + (0x8*x))
+#define SDRAM_WIN_CTRL_REG(x)	(0x20184 + (0x8*x))
+
+static phys_addr_t mvebu_internal_reg_base(void)
+{
+	struct device_node *np;
+	__be32 in_addr[2];
+
+	np = of_find_node_by_name(NULL, "internal-regs");
+	BUG_ON(!np);
+
+	/*
+	 * Ask the DT what is the internal register address on this
+	 * platform. In the mvebu-mbus DT binding, 0xf0010000
+	 * corresponds to the internal register window.
+	 */
+	in_addr[0] = cpu_to_be32(0xf0010000);
+	in_addr[1] = 0x0;
+
+	return of_translate_address(np, in_addr);
+}
+
+static void mvebu_pm_store_bootinfo(void)
+{
+	u32 *store_addr;
+	phys_addr_t resume_pc;
+
+	store_addr = phys_to_virt(BOOT_INFO_ADDR);
+	resume_pc = virt_to_phys(armada_370_xp_cpu_resume);
+
+	/*
+	 * The bootloader expects the first two words to be a magic
+	 * value (BOOT_MAGIC_WORD), followed by the address of the
+	 * resume code to jump to. Then, it expects a sequence of
+	 * (address, value) pairs, which can be used to restore the
+	 * value of certain registers. This sequence must end with the
+	 * BOOT_MAGIC_LIST_END magic value.
+	 */
+
+	writel(BOOT_MAGIC_WORD, store_addr++);
+	writel(resume_pc, store_addr++);
+
+	/*
+	 * Some platforms remap their internal register base address
+	 * to 0xf1000000. However, out of reset, window 12 starts at
+	 * 0xf0000000 and ends at 0xf7ffffff, which would overlap with
+	 * the internal registers. Therefore, disable window 12.
+	 */
+	writel(MBUS_WINDOW_12_CTRL, store_addr++);
+	writel(0x0, store_addr++);
+
+	/*
+	 * Set the internal register base address to the value
+	 * expected by Linux, as read from the Device Tree.
+	 */
+	writel(MBUS_INTERNAL_REG_ADDRESS, store_addr++);
+	writel(mvebu_internal_reg_base(), store_addr++);
+
+	/*
+	 * Ask the mvebu-mbus driver to store the SDRAM window
+	 * configuration, which has to be restored by the bootloader
+	 * before re-entering the kernel on resume.
+	 */
+	store_addr += mvebu_mbus_save_cpu_target(store_addr);
+
+	writel(BOOT_MAGIC_LIST_END, store_addr);
+}
+
+static int mvebu_pm_enter(suspend_state_t state)
+{
+	if (state != PM_SUSPEND_MEM)
+		return -EINVAL;
+
+	cpu_pm_enter();
+
+	mvebu_pm_store_bootinfo();
+	cpu_suspend(0, mvebu_pm_powerdown);
+
+	outer_resume();
+
+	mvebu_v7_pmsu_idle_exit();
+
+	set_cpu_coherent();
+
+	cpu_pm_exit();
+
+	return 0;
+}
+
+static const struct platform_suspend_ops mvebu_pm_ops = {
+	.enter = mvebu_pm_enter,
+	.valid = suspend_valid_only_mem,
+};
+
+int mvebu_pm_init(void (*board_pm_enter)(void __iomem *sdram_reg, u32 srcmd))
+{
+	struct device_node *np;
+	struct resource res;
+
+	if (!of_machine_is_compatible("marvell,armadaxp"))
+		return -ENODEV;
+
+	np = of_find_compatible_node(NULL, NULL,
+				     "marvell,armada-xp-sdram-controller");
+	if (!np)
+		return -ENODEV;
+
+	if (of_address_to_resource(np, 0, &res)) {
+		of_node_put(np);
+		return -ENODEV;
+	}
+
+	if (!request_mem_region(res.start, resource_size(&res),
+				np->full_name)) {
+		of_node_put(np);
+		return -EBUSY;
+	}
+
+	sdram_ctrl = ioremap(res.start, resource_size(&res));
+	if (!sdram_ctrl) {
+		release_mem_region(res.start, resource_size(&res));
+		of_node_put(np);
+		return -ENOMEM;
+	}
+
+	of_node_put(np);
+
+	mvebu_board_pm_enter = board_pm_enter;
+
+	suspend_set_ops(&mvebu_pm_ops);
+
+	return 0;
+}