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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: Philip Avinash <avinashphilip@ti.com>
Signed-off-by: Pekon Gupta <pekon@ti.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
avinash philip 2013-06-18 00:16:39 +05:30 committed by David Woodhouse
parent ba2694da2c
commit 11f164d111
1 changed files with 117 additions and 0 deletions
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117
drivers/mtd/devices/elm.c
View File

@ -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,