Message-ID: <470a5b7b7a6cc2c83e2a7bb6007789e53f76c6ea.1417029919.git.d-gerlach@ti.com>
Date:	Wed, 26 Nov 2014 15:39:06 -0600
From:	Dave Gerlach <d-gerlach@...com>
To:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<devicetree@...r.kernel.org>
CC:	Tony Lindgren <tony@...mide.com>,
	Benoit Cousson <bcousson@...libre.com>,
	Kevin Hilman <khilman@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dave Gerlach <d-gerlach@...com>
Subject: [RFC PATCH 2/3] memory: ti-emif-sram: introduce relocatable suspend/resume handlers

Certain SoCs like Texas Instruments AM335x and AM437x require parts
of the EMIF PM code to run late in the suspend sequence from SRAM,
such as saving and restoring the EMIF context and placing the memory
into self-refresh.

One requirement for these SoC's to suspend and enter it's lowest power
mode, called DeepSleep0, is that the PER power domain must be shut
off. Because the EMIF (DDR Controller) resides within this power
domain, it will lose context during a suspend operation, so we must
save it to restore once we resume. However, we cannot execute this
code from external memory, as it is not available at this point, so
the code must be executed late in the suspend path from SRAM.

This patch introduces a ti-emif-sram driver that includes several
functions written in ARM ASM that are relocatable so the PM SRAM
code can use them. It can export a table containing the absolute
addresses of the available PM functions so that other SRAM code
can branch to them. This code is required for suspend/resume on
AM335x and AM437x to work.

Signed-off-by: Dave Gerlach <d-gerlach@...com>
---
 drivers/memory/Kconfig           |  10 ++
 drivers/memory/Makefile          |   3 +
 drivers/memory/emif.h            |   8 ++
 drivers/memory/ti-emif-sram-pm.S | 233 +++++++++++++++++++++++++++++++++++++++
 drivers/memory/ti-emif-sram.c    | 195 ++++++++++++++++++++++++++++++++
 include/linux/ti-emif-sram.h     |  26 +++++
 6 files changed, 475 insertions(+)
 create mode 100644 drivers/memory/ti-emif-sram-pm.S
 create mode 100644 drivers/memory/ti-emif-sram.c
 create mode 100644 include/linux/ti-emif-sram.h

diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
index 6d91c27..02b778e 100644
--- a/drivers/memory/Kconfig
+++ b/drivers/memory/Kconfig
@@ -41,6 +41,16 @@ config TI_EMIF
 	  parameters and other settings during frequency, voltage and
 	  temperature changes
 
+config TI_EMIF_SRAM
+	bool "Texas Instruments EMIF SRAM driver"
+	depends on SOC_AM33XX
+	help
+	  This driver is for the EMIF module available on Texas Instruments
+	  AM33XX SoCs and is required for PM. Certain parts of the EMIF PM
+	  code must run from on-chip SRAM late in the suspend sequence so
+	  this driver provides several relocatable PM functions for the SoC
+	  PM code to use.
+
 config MVEBU_DEVBUS
 	bool "Marvell EBU Device Bus Controller"
 	default y
diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
index c32d319..42888c2 100644
--- a/drivers/memory/Makefile
+++ b/drivers/memory/Makefile
@@ -13,3 +13,6 @@ obj-$(CONFIG_FSL_IFC)		+= fsl_ifc.o
 obj-$(CONFIG_MVEBU_DEVBUS)	+= mvebu-devbus.o
 obj-$(CONFIG_TEGRA20_MC)	+= tegra20-mc.o
 obj-$(CONFIG_TEGRA30_MC)	+= tegra30-mc.o
+obj-$(CONFIG_TI_EMIF_SRAM)	+= ti-emif-sram.o ti-emif-sram-pm.o
+
+AFLAGS_ti-emif-sram-pm.o	:=-Wa,-march=armv7-a
diff --git a/drivers/memory/emif.h b/drivers/memory/emif.h
index bfe08ba..8e86eb2 100644
--- a/drivers/memory/emif.h
+++ b/drivers/memory/emif.h
@@ -585,5 +585,13 @@ struct emif_regs {
 	u32 ext_phy_ctrl_3_shdw;
 	u32 ext_phy_ctrl_4_shdw;
 };
+
+struct ti_emif_pm_functions;
+
+extern unsigned int ti_emif_sram;
+extern unsigned int ti_emif_sram_sz;
+extern void __iomem *ti_emif_base_addr_virt;
+extern void __iomem *ti_emif_base_addr_phys;
+extern struct ti_emif_pm_functions ti_emif_pm;
 #endif /* __ASSEMBLY__ */
 #endif /* __EMIF_H */
diff --git a/drivers/memory/ti-emif-sram-pm.S b/drivers/memory/ti-emif-sram-pm.S
new file mode 100644
index 0000000..49b0be4
--- /dev/null
+++ b/drivers/memory/ti-emif-sram-pm.S
@@ -0,0 +1,233 @@
+/*
+ * Low level PM code for TI EMIF
+ *
+ * Copyright (C) 2014 Texas Instruments Incorporated - http://www.ti.com/
+ *	Dave Gerlach
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/linkage.h>
+#include <asm/memory.h>
+#include <asm/assembler.h>
+
+#include "emif.h"
+
+#define EMIF_POWER_MGMT_WAIT_SELF_REFRESH_8192_CYCLES	0x00a0
+#define EMIF_POWER_MGMT_SR_TIMER_MASK			0x00f0
+#define EMIF_POWER_MGMT_SELF_REFRESH_MODE		0x0200
+#define EMIF_POWER_MGMT_SELF_REFRESH_MODE_MASK		0x0700
+
+#define EMIF_SDCFG_TYPE_DDR2				0x2 << SDRAM_TYPE_SHIFT
+#define EMIF_STATUS_READY				0x4
+
+	.text
+	.align 3
+
+ENTRY(ti_emif_sram)
+
+/*
+ * void ti_emif_save_context(void)
+ *
+ * Used during suspend to save the context of all required EMIF registers
+ * to local memory if the EMIF is going to lose context during the sleep
+ * transition. Operates on the VIRTUAL address of the EMIF.
+ */
+ENTRY(ti_emif_save_context)
+	stmfd   sp!, {r4 - r11, lr}     @ save registers on stack
+
+	ldr	r0, ti_emif_base_addr_virt
+
+	/* Save EMIF configuration */
+	ldr	r1, [r0, #EMIF_SDRAM_CONFIG]
+	str	r1, emif_sdcfg_val
+	ldr	r1, [r0, #EMIF_SDRAM_REFRESH_CONTROL]
+	str	r1, emif_ref_ctrl_val
+	ldr	r1, [r0, #EMIF_SDRAM_TIMING_1]
+	str	r1, emif_timing1_val
+	ldr	r1, [r0, #EMIF_SDRAM_TIMING_2]
+	str	r1, emif_timing2_val
+	ldr	r1, [r0, #EMIF_SDRAM_TIMING_3]
+	str	r1, emif_timing3_val
+	ldr	r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
+	str	r1, emif_pmcr_val
+	ldr	r1, [r0, #EMIF_POWER_MANAGEMENT_CTRL_SHDW]
+	str	r1, emif_pmcr_shdw_val
+	ldr	r1, [r0, #EMIF_SDRAM_OUTPUT_IMPEDANCE_CALIBRATION_CONFIG]
+	str	r1, emif_zqcfg_val
+	ldr	r1, [r0, #EMIF_DDR_PHY_CTRL_1]
+	str	r1, emif_rd_lat_val
+
+	ldmfd	sp!, {r4 - r11, pc}	@ restore regs and return
+ENDPROC(ti_emif_save_context)
+
+/*
+ * void ti_emif_restore_context(void)
+ *
+ * Used during resume to restore the context of all required EMIF registers
+ * from local memory after the EMIF has lost context during a sleep transition.
+ * Operates on the PHYSICAL address of the EMIF.
+ */
+ENTRY(ti_emif_restore_context)
+	stmfd   sp!, {r4 - r11, lr}     @ save registers on stack
+
+	ldr     r0, ti_emif_base_addr_phys
+
+	/* Config EMIF Timings */
+	ldr	r1, emif_rd_lat_val
+	str	r1, [r0, #EMIF_DDR_PHY_CTRL_1]
+	str	r1, [r0, #EMIF_DDR_PHY_CTRL_1_SHDW]
+	ldr	r1, emif_timing1_val
+	str	r1, [r0, #EMIF_SDRAM_TIMING_1]
+	str	r1, [r0, #EMIF_SDRAM_TIMING_1_SHDW]
+	ldr	r1, emif_timing2_val
+	str	r1, [r0, #EMIF_SDRAM_TIMING_2]
+	str	r1, [r0, #EMIF_SDRAM_TIMING_2_SHDW]
+	ldr	r1, emif_timing3_val
+	str	r1, [r0, #EMIF_SDRAM_TIMING_3]
+	str	r1, [r0, #EMIF_SDRAM_TIMING_3_SHDW]
+	ldr	r1, emif_ref_ctrl_val
+	str	r1, [r0, #EMIF_SDRAM_REFRESH_CONTROL]
+	str	r1, [r0, #EMIF_SDRAM_REFRESH_CTRL_SHDW]
+	ldr	r1, emif_pmcr_shdw_val
+	str	r1, [r0, #EMIF_POWER_MANAGEMENT_CTRL_SHDW]
+
+	/*
+	 * Output impedence calib needed only for DDR3
+	 * but since the initial state of this will be
+	 * disabled for DDR2 no harm in restoring the
+	 * old configuration
+	 */
+	ldr	r1, emif_zqcfg_val
+	str	r1, [r0, #EMIF_SDRAM_OUTPUT_IMPEDANCE_CALIBRATION_CONFIG]
+
+	/* Write to sdcfg last for DDR2 only */
+	ldr	r1, emif_sdcfg_val
+	and	r2, r1, #SDRAM_TYPE_MASK
+	cmp	r2, #EMIF_SDCFG_TYPE_DDR2
+	streq	r1, [r0, #EMIF_SDRAM_CONFIG]
+
+	ldmfd	sp!, {r4 - r11, pc}	@ restore regs and return
+ENDPROC(ti_emif_restore_context)
+
+/*
+ * void ti_emif_enter_sr(void)
+ *
+ * Programs the EMIF to tell the SDRAM to enter into self-refresh
+ * mode during a sleep transition. Operates on the VIRTUAL address
+ * of the EMIF.
+ */
+ENTRY(ti_emif_enter_sr)
+	stmfd   sp!, {r4 - r11, lr}     @ save registers on stack
+
+	ldr	r0, ti_emif_base_addr_virt
+
+	ldr	r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
+	bic	r1, r1, #EMIF_POWER_MGMT_SELF_REFRESH_MODE_MASK
+	orr	r1, r1, #EMIF_POWER_MGMT_SELF_REFRESH_MODE
+	str	r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
+
+	ldmfd	sp!, {r4 - r11, pc}	@ restore regs and return
+ENDPROC(ti_emif_enter_sr)
+
+/*
+ * void ti_emif_exit_sr(void)
+ *
+ * Programs the EMIF to tell the SDRAM to exit self-refresh mode
+ * after a sleep transition. Operates on the PHYSICAL address of
+ * the EMIF.
+ */
+ENTRY(ti_emif_exit_sr)
+	stmfd   sp!, {r4 - r11, lr}     @ save registers on stack
+
+	ldr	r0, ti_emif_base_addr_phys
+
+	/*
+	 * Toggle EMIF to exit refresh mode:
+	 * if EMIF lost context, PWR_MGT_CTRL is currently 0, writing disable
+	 *   (0x0), wont do diddly squat! so do a toggle from SR(0x2) to disable
+	 *   (0x0) here.
+	 * *If* EMIF did not lose context, nothing broken as we write the same
+	 *   value(0x2) to reg before we write a disable (0x0).
+	 */
+	ldr	r1, emif_pmcr_val
+	bic	r1, r1, #EMIF_POWER_MGMT_SELF_REFRESH_MODE_MASK
+	orr	r1, r1, #EMIF_POWER_MGMT_SELF_REFRESH_MODE
+	str	r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
+	bic	r1, r1, #EMIF_POWER_MGMT_SELF_REFRESH_MODE_MASK
+	str	r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
+
+        /* Wait for EMIF to become ready */
+1:	ldr     r1, [r0, #EMIF_STATUS]
+	tst     r1, #EMIF_STATUS_READY
+	beq     1b
+
+	ldmfd	sp!, {r4 - r11, pc}	@ restore regs and return
+ENDPROC(ti_emif_exit_sr)
+
+/*
+ * void ti_emif_abort_sr(void)
+ *
+ * Disables self-refresh after a failed transition to a low-power
+ * state so the kernel can jump back to DDR and follow abort path.
+ * Operates on the VIRTUAL address of the EMIF.
+ */
+ENTRY(ti_emif_abort_sr)
+	stmfd   sp!, {r4 - r11, lr}     @ save registers on stack
+
+	ldr	r0, ti_emif_base_addr_virt
+
+	ldr	r1, emif_pmcr_val
+	bic	r1, r1, #EMIF_POWER_MGMT_SELF_REFRESH_MODE_MASK
+	str	r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
+
+	/* Wait for EMIF to become ready */
+1:	ldr     r1, [r0, #EMIF_STATUS]
+	tst     r1, #EMIF_STATUS_READY
+	beq     1b
+
+	ldmfd	sp!, {r4 - r11, pc}	@ restore regs and return
+ENDPROC(ti_emif_abort_sr)
+
+	.align 3
+/* DDR related defines */
+emif_addr_virt:
+	.word	0xDEADBEEF
+emif_rd_lat_val:
+	.word	0xDEADBEEF
+emif_timing1_val:
+	.word	0xDEADBEEF
+emif_timing2_val:
+	.word	0xDEADBEEF
+emif_timing3_val:
+	.word	0xDEADBEEF
+emif_sdcfg_val:
+	.word	0xDEADBEEF
+emif_ref_ctrl_val:
+	.word	0xDEADBEEF
+emif_zqcfg_val:
+	.word	0xDEADBEEF
+emif_pmcr_val:
+	.word	0xDEADBEEF
+emif_pmcr_shdw_val:
+	.word	0xDEADBEEF
+
+ENTRY(ti_emif_base_addr_virt)
+        .word   0x00000000
+ENTRY(ti_emif_base_addr_phys)
+        .word   0x00000000
+ENTRY(ti_emif_pm)
+	.word	ti_emif_save_context - ti_emif_sram
+	.word	ti_emif_restore_context - ti_emif_sram
+	.word	ti_emif_enter_sr - ti_emif_sram
+	.word	ti_emif_exit_sr - ti_emif_sram
+	.word	ti_emif_abort_sr - ti_emif_sram
+ENTRY(ti_emif_sram_sz)
+        .word   . - ti_emif_save_context
diff --git a/drivers/memory/ti-emif-sram.c b/drivers/memory/ti-emif-sram.c
new file mode 100644
index 0000000..e843a3b
--- /dev/null
+++ b/drivers/memory/ti-emif-sram.c
@@ -0,0 +1,195 @@
+/*
+ * TI AM33XX SRAM EMIF Driver
+ *
+ * Copyright (C) 2014 Texas Instruments Inc.
+ *          Dave Gerlach <d-gerlach@...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 as published by the Free Software Foundation.
+ *
+ * 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/err.h>
+#include <linux/genalloc.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#include <asm/fncpy.h>
+
+#include "emif.h"
+
+#define EMIF_POWER_MGMT_WAIT_SELF_REFRESH_8192_CYCLES		0x00a0
+
+struct ti_emif_pm_functions {
+	u32 save_context;
+	u32 restore_context;
+	u32 enter_sr;
+	u32 exit_sr;
+	u32 abort_sr;
+} __packed;
+
+static void __iomem *ti_emif_sram_phys;
+static void __iomem *ti_emif_sram_virt;
+
+static u32 sram_suspend_address(unsigned long fn_offset)
+{
+	return (unsigned long)ti_emif_sram_virt + fn_offset;
+}
+
+static u32 sram_resume_address(unsigned long fn_offset)
+{
+	return (unsigned long)ti_emif_sram_phys + fn_offset;
+}
+
+static int ti_emif_push_sram(struct device_node *np)
+{
+	struct gen_pool *sram_pool;
+	phys_addr_t ocmcram_location;
+
+	sram_pool = of_get_named_gen_pool(np, "sram", 0);
+
+	if (!sram_pool)
+		pr_warn("PM: %s: Unable to allocate sram pool for ocmcram\n",
+			__func__);
+
+	ocmcram_location = gen_pool_alloc(sram_pool, ti_emif_sram_sz);
+	if (!ocmcram_location)
+		return -EINVAL;
+
+	/* Save physical address to calculate resume offset during pm init */
+	ti_emif_sram_phys = (void *)gen_pool_virt_to_phys(sram_pool,
+							  ocmcram_location);
+	ti_emif_sram_virt = (void *)fncpy((void *)ocmcram_location,
+					 &ti_emif_sram,
+					 ti_emif_sram_sz);
+
+	/*
+	 * These functions are called during suspend path while MMU is
+	 * still on so add virtual base to offset for absolute address
+	 */
+	ti_emif_pm.save_context = sram_suspend_address(ti_emif_pm.save_context);
+	ti_emif_pm.enter_sr = sram_suspend_address(ti_emif_pm.enter_sr);
+	ti_emif_pm.abort_sr = sram_suspend_address(ti_emif_pm.abort_sr);
+
+	/*
+	 * These are called during resume path when MMU is not enabled
+	 * so physical address is used instead
+	 */
+	ti_emif_pm.restore_context =
+		sram_resume_address(ti_emif_pm.restore_context);
+	ti_emif_pm.exit_sr = sram_resume_address(ti_emif_pm.exit_sr);
+
+	return 0;
+}
+
+/*
+ * Due to Usage Note 3.1.2 "DDR3: JEDEC Compliance for Maximum
+ * Self-Refresh Command Limit" found in AM335x Silicon Errata
+ * (Document SPRZ360F Revised November 2013) we must configure
+ * the self refresh delay timer to 0xA (8192 cycles) to avoid
+ * generating too many refresh command from the EMIF.
+ */
+static void ti_emif_configure_sr_delay(void)
+{
+	writel(EMIF_POWER_MGMT_WAIT_SELF_REFRESH_8192_CYCLES,
+	       (void *)(ti_emif_base_addr_virt +
+			EMIF_POWER_MANAGEMENT_CONTROL));
+
+	writel(EMIF_POWER_MGMT_WAIT_SELF_REFRESH_8192_CYCLES,
+	       (void *)(ti_emif_base_addr_virt +
+			EMIF_POWER_MANAGEMENT_CTRL_SHDW));
+}
+
+/**
+ * ti_emif_copy_pm_function_table - copy mapping of pm funcs in sram
+ * @dst: void * to address that table should be copied
+ *
+ * Returns 0 if success other error code if table is not available
+ */
+int ti_emif_copy_pm_function_table(void *dst)
+{
+	if (!ti_emif_sram_virt)
+		return -ENODEV;
+
+	memcpy_toio(dst, &ti_emif_pm, sizeof(ti_emif_pm));
+
+	return 0;
+}
+
+/**
+ * ti_emif_get_mem_type - return type for memory type in use
+ *
+ * Returns memory type value read from EMIF or error code if fails
+ */
+int ti_emif_get_mem_type(void)
+{
+	unsigned long temp;
+
+	if (!ti_emif_base_addr_virt || IS_ERR(ti_emif_base_addr_virt))
+		return -ENODEV;
+
+	temp = readl((void *)ti_emif_base_addr_virt + EMIF_SDRAM_CONFIG);
+
+	temp = (temp & SDRAM_TYPE_MASK) >> SDRAM_TYPE_SHIFT;
+	return temp;
+}
+
+static const struct of_device_id ti_emif_of_match[] = {
+	{ .compatible = "ti,am3352-emif", },
+	{},
+};
+
+static int ti_emif_probe(struct platform_device *pdev)
+{
+	int ret = -ENODEV;
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ti_emif_base_addr_virt = devm_ioremap_resource(dev, res);
+	if (IS_ERR(ti_emif_base_addr_virt)) {
+		dev_err(dev, "could not ioremap emif mem\n");
+		return PTR_ERR(ti_emif_base_addr_virt);
+	}
+
+	ti_emif_base_addr_phys = (void *)res->start;
+
+	ti_emif_configure_sr_delay();
+
+	ret = ti_emif_push_sram(np);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ti_emif_remove(struct platform_device *pdev)
+{
+	return 0;
+}
+
+static struct platform_driver ti_emif_driver = {
+	.probe = ti_emif_probe,
+	.remove = ti_emif_remove,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = of_match_ptr(ti_emif_of_match),
+	},
+};
+
+module_platform_driver(ti_emif_driver);
+
+MODULE_AUTHOR("Dave Gerlach <d-gerlach@...com>");
+MODULE_DESCRIPTION("Texas Instruments SRAM EMIF driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" KBUILD_MODNAME);
diff --git a/include/linux/ti-emif-sram.h b/include/linux/ti-emif-sram.h
new file mode 100644
index 0000000..e0ec7fa
--- /dev/null
+++ b/include/linux/ti-emif-sram.h
@@ -0,0 +1,26 @@
+/*
+ * TI AM33XX EMIF Routines
+ *
+ * Copyright (C) 2014 Texas Instruments Inc.
+ *          Dave Gerlach <d-gerlach@...com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#ifndef __LINUX_TI_EMIF_H
+#define __LINUX_TI_EMIF_H
+
+#ifdef CONFIG_TI_EMIF_SRAM
+int ti_emif_copy_pm_function_table(void *dst);
+int ti_emif_get_mem_type(void);
+#else
+static inline int ti_emif_copy_pm_function_table(void *dst) { return -ENODEV; }
+static inline int ti_emif_get_mem_type(void) { return -ENODEV; }
+#endif /* CONFIG_TI_EMIF_SRAM */
+#endif /* __LINUX_TI_EMIF_H */
-- 
2.1.0

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