[PATCH v2 3/4] mtd: devices: elm: Low power transition support

[Philip Avinash]

In low power modes of AM335X platforms, peripherals power is cut off.
This patch supports low power sleep transition support for ELM driver.

Signed-off-by: Philip Avinash <avinashphi...@ti.com>
---
 drivers/mtd/devices/elm.c |   40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/drivers/mtd/devices/elm.c b/drivers/mtd/devices/elm.c
index f034239..a9ac8f2 100644
--- a/drivers/mtd/devices/elm.c
+++ b/drivers/mtd/devices/elm.c
@@ -20,6 +20,7 @@
 #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>
 
@@ -62,6 +63,7 @@ struct elm_info {
        struct completion elm_completion;
        struct list_head list;
        enum bch_ecc bch_type;
+       bool idle;
 };
 
 static LIST_HEAD(elm_devices);
@@ -86,9 +88,11 @@ void elm_config(struct device *dev, enum bch_ecc bch_type)
        u32 reg_val;
        struct elm_info *info = dev_get_drvdata(dev);
 
+       info->idle = true;
        reg_val = (bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
        elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
        info->bch_type = bch_type;
+       info->idle = false;
 }
 EXPORT_SYMBOL(elm_config);
 
@@ -280,6 +284,7 @@ void elm_decode_bch_error_page(struct device *dev, u8 
*ecc_calc,
        struct elm_info *info = dev_get_drvdata(dev);
        u32 reg_val;
 
+       info->idle = true;
        /* Enable page mode interrupt */
        reg_val = elm_read_reg(info, ELM_IRQSTATUS);
        elm_write_reg(info, ELM_IRQSTATUS, reg_val & INTR_STATUS_PAGE_VALID);
@@ -298,6 +303,7 @@ void elm_decode_bch_error_page(struct device *dev, u8 
*ecc_calc,
        reg_val = elm_read_reg(info, ELM_IRQENABLE);
        elm_write_reg(info, ELM_IRQENABLE, reg_val & ~INTR_EN_PAGE_MASK);
        elm_error_correction(info, err_vec);
+       info->idle = false;
 }
 EXPORT_SYMBOL(elm_decode_bch_error_page);
 
@@ -368,6 +374,7 @@ static int elm_probe(struct platform_device *pdev)
        INIT_LIST_HEAD(&info->list);
        list_add(&info->list, &elm_devices);
        platform_set_drvdata(pdev, info);
+       info->idle = false;
        return ret;
 }
 
@@ -379,6 +386,38 @@ static int elm_remove(struct platform_device *pdev)
        return 0;
 }
 
+static int elm_suspend(struct device *dev)
+{
+       struct elm_info *info = dev_get_drvdata(dev);
+       wait_queue_head_t wq;
+       DECLARE_WAITQUEUE(wait, current);
+
+       init_waitqueue_head(&wq);
+       while (1) {
+               /* Make sure that ELM not running */
+               if (info->idle) {
+                       add_wait_queue(&wq, &wait);
+                       schedule();
+                       remove_wait_queue(&wq, &wait);
+               } else {
+                       break;
+               }
+       }
+       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_config(dev, info->bch_type);
+       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" },
@@ -392,6 +431,7 @@ 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,
-- 
1.7.9.5

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