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Commit 11f164d1 authored by avinash philip's avatar avinash philip Committed by David Woodhouse
Browse files

mtd: devices: elm: Low power transition support 



ELM is used for locating bit-flip errors in when using BCH ECC scheme.
This patch adds suspend/resume support for leaf level ELM driver,
And also provides ELM register context save & restore support, so that
configurations are preserved across hardware power-off/on transitions.

Signed-off-by: default avatarPhilip Avinash <avinashphilip@ti.com>
Signed-off-by: default avatarPekon Gupta <pekon@ti.com>
Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent ba2694da

drivers/mtd/devices/elm.c

+117 −0
Original line number Diff line number Diff line
@@ -20,14 +20,21 @@ 
#include <linux/interrupt.h>

#include <linux/io.h>

#include <linux/of.h>

#include <linux/sched.h>

#include <linux/pm_runtime.h>

#include <linux/platform_data/elm.h>



#define ELM_SYSCONFIG			0x010

#define ELM_IRQSTATUS			0x018

#define ELM_IRQENABLE			0x01c

#define ELM_LOCATION_CONFIG		0x020

#define ELM_PAGE_CTRL			0x080

#define ELM_SYNDROME_FRAGMENT_0		0x400

#define ELM_SYNDROME_FRAGMENT_1		0x404

#define ELM_SYNDROME_FRAGMENT_2		0x408

#define ELM_SYNDROME_FRAGMENT_3		0x40c

#define ELM_SYNDROME_FRAGMENT_4		0x410

#define ELM_SYNDROME_FRAGMENT_5		0x414

#define ELM_SYNDROME_FRAGMENT_6		0x418

#define ELM_LOCATION_STATUS		0x800

#define ELM_ERROR_LOCATION_0		0x880
@@ -56,12 +63,27 @@ 
#define SYNDROME_FRAGMENT_REG_SIZE	0x40

#define ERROR_LOCATION_SIZE		0x100



struct elm_registers {

	u32 elm_irqenable;

	u32 elm_sysconfig;

	u32 elm_location_config;

	u32 elm_page_ctrl;

	u32 elm_syndrome_fragment_6[ERROR_VECTOR_MAX];

	u32 elm_syndrome_fragment_5[ERROR_VECTOR_MAX];

	u32 elm_syndrome_fragment_4[ERROR_VECTOR_MAX];

	u32 elm_syndrome_fragment_3[ERROR_VECTOR_MAX];

	u32 elm_syndrome_fragment_2[ERROR_VECTOR_MAX];

	u32 elm_syndrome_fragment_1[ERROR_VECTOR_MAX];

	u32 elm_syndrome_fragment_0[ERROR_VECTOR_MAX];

};



struct elm_info {

	struct device *dev;

	void __iomem *elm_base;

	struct completion elm_completion;

	struct list_head list;

	enum bch_ecc bch_type;

	struct elm_registers elm_regs;

};



static LIST_HEAD(elm_devices);
@@ -384,6 +406,100 @@ static int elm_remove(struct platform_device *pdev) 
	return 0;

}



/**

 * elm_context_save

 * saves ELM configurations to preserve them across Hardware powered-down

 */

static int elm_context_save(struct elm_info *info)

{

	struct elm_registers *regs = &info->elm_regs;

	enum bch_ecc bch_type = info->bch_type;

	u32 offset = 0, i;



	regs->elm_irqenable       = elm_read_reg(info, ELM_IRQENABLE);

	regs->elm_sysconfig       = elm_read_reg(info, ELM_SYSCONFIG);

	regs->elm_location_config = elm_read_reg(info, ELM_LOCATION_CONFIG);

	regs->elm_page_ctrl       = elm_read_reg(info, ELM_PAGE_CTRL);

	for (i = 0; i < ERROR_VECTOR_MAX; i++) {

		offset = i * SYNDROME_FRAGMENT_REG_SIZE;

		switch (bch_type) {

		case BCH8_ECC:

			regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,

					ELM_SYNDROME_FRAGMENT_3 + offset);

			regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,

					ELM_SYNDROME_FRAGMENT_2 + offset);

		case BCH4_ECC:

			regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,

					ELM_SYNDROME_FRAGMENT_1 + offset);

			regs->elm_syndrome_fragment_0[i] = elm_read_reg(info,

					ELM_SYNDROME_FRAGMENT_0 + offset);

		default:

			return -EINVAL;

		}

		/* ELM SYNDROME_VALID bit in SYNDROME_FRAGMENT_6[] needs

		 * to be saved for all BCH schemes*/

		regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,

					ELM_SYNDROME_FRAGMENT_6 + offset);

	}

	return 0;

}



/**

 * elm_context_restore

 * writes configurations saved duing power-down back into ELM registers

 */

static int elm_context_restore(struct elm_info *info)

{

	struct elm_registers *regs = &info->elm_regs;

	enum bch_ecc bch_type = info->bch_type;

	u32 offset = 0, i;



	elm_write_reg(info, ELM_IRQENABLE,	 regs->elm_irqenable);

	elm_write_reg(info, ELM_SYSCONFIG,	 regs->elm_sysconfig);

	elm_write_reg(info, ELM_LOCATION_CONFIG, regs->elm_location_config);

	elm_write_reg(info, ELM_PAGE_CTRL,	 regs->elm_page_ctrl);

	for (i = 0; i < ERROR_VECTOR_MAX; i++) {

		offset = i * SYNDROME_FRAGMENT_REG_SIZE;

		switch (bch_type) {

		case BCH8_ECC:

			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,

					regs->elm_syndrome_fragment_3[i]);

			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,

					regs->elm_syndrome_fragment_2[i]);

		case BCH4_ECC:

			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,

					regs->elm_syndrome_fragment_1[i]);

			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_0 + offset,

					regs->elm_syndrome_fragment_0[i]);

		default:

			return -EINVAL;

		}

		/* ELM_SYNDROME_VALID bit to be set in last to trigger FSM */

		elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,

					regs->elm_syndrome_fragment_6[i] &

							 ELM_SYNDROME_VALID);

	}

	return 0;

}



static int elm_suspend(struct device *dev)

{

	struct elm_info *info = dev_get_drvdata(dev);

	elm_context_save(info);

	pm_runtime_put_sync(dev);

	return 0;

}



static int elm_resume(struct device *dev)

{

	struct elm_info *info = dev_get_drvdata(dev);

	pm_runtime_get_sync(dev);

	elm_context_restore(info);

	return 0;

}



static SIMPLE_DEV_PM_OPS(elm_pm_ops, elm_suspend, elm_resume);



#ifdef CONFIG_OF

static const struct of_device_id elm_of_match[] = {

	{ .compatible = "ti,am3352-elm" },
@@ -397,6 +513,7 @@ static struct platform_driver elm_driver = { 
		.name	= "elm",

		.owner	= THIS_MODULE,

		.of_match_table = of_match_ptr(elm_of_match),

		.pm	= &elm_pm_ops,

	},

	.probe	= elm_probe,

	.remove	= elm_remove,