mtd: sh_flctl: Add power management with QoS request

Adds power management code with fine granularity. Every flash control
command is enclosed by runtime_put()/get()s. To make sure that no
overhead is generated by too frequent power state switches, a quality of
service request is issued.

Signed-off-by: Bastian Hecht <hechtb@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

2 files changed, 45 insertions, 9 deletions

diff --git a/drivers/mtd/nand/sh_flctl.c b/drivers/mtd/nand/sh_flctl.c
index d0f1f3c13e76..2ee9a1b50a22 100644
--- a/drivers/mtd/nand/sh_flctl.c
+++ b/drivers/mtd/nand/sh_flctl.c
@@ -26,6 +26,7 @@
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 
 #include <linux/mtd/mtd.h>
@@ -515,6 +516,8 @@ static void flctl_cmdfunc(struct mtd_info *mtd, unsigned int command,
         struct sh_flctl *flctl = mtd_to_flctl(mtd);
         uint32_t read_cmd = 0;
 
+        pm_runtime_get_sync(&flctl->pdev->dev);
+
         flctl->read_bytes = 0;
         if (command != NAND_CMD_PAGEPROG)
                 flctl->index = 0;
@@ -670,7 +673,7 @@ static void flctl_cmdfunc(struct mtd_info *mtd, unsigned int command,
         default:
                 break;
         }
-        return;
+        goto runtime_exit;
 
 read_normal_exit:
         writel(flctl->read_bytes, FLDTCNTR(flctl));     /* set read size */
@@ -678,23 +681,47 @@ read_normal_exit:
         start_translation(flctl);
         read_fiforeg(flctl, flctl->read_bytes, 0);
         wait_completion(flctl);
+runtime_exit:
+        pm_runtime_put_sync(&flctl->pdev->dev);
         return;
 }
 
 static void flctl_select_chip(struct mtd_info *mtd, int chipnr)
 {
         struct sh_flctl *flctl = mtd_to_flctl(mtd);
+        int ret;
 
         switch (chipnr) {
         case -1:
                 flctl->flcmncr_base &= ~CE0_ENABLE;
+
+                pm_runtime_get_sync(&flctl->pdev->dev);
                 writel(flctl->flcmncr_base, FLCMNCR(flctl));
+
+                if (flctl->qos_request) {
+                        dev_pm_qos_remove_request(&flctl->pm_qos);
+                        flctl->qos_request = 0;
+                }
+
+                pm_runtime_put_sync(&flctl->pdev->dev);
                 break;
         case 0:
                 flctl->flcmncr_base |= CE0_ENABLE;
-                writel(flctl->flcmncr_base, FLCMNCR(flctl));
-                if (flctl->holden)
+
+                if (!flctl->qos_request) {
+                        ret = dev_pm_qos_add_request(&flctl->pdev->dev,
+                                                        &flctl->pm_qos, 100);
+                        if (ret < 0)
+                                dev_err(&flctl->pdev->dev,
+                                        "PM QoS request failed: %d\n", ret);
+                        flctl->qos_request = 1;
+                }
+
+                if (flctl->holden) {
+                        pm_runtime_get_sync(&flctl->pdev->dev);
                         writel(HOLDEN, FLHOLDCR(flctl));
+                        pm_runtime_put_sync(&flctl->pdev->dev);
+                }
                 break;
         default:
                 BUG();
@@ -835,13 +862,13 @@ static int __devinit flctl_probe(struct platform_device *pdev)
         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         if (!res) {
                 dev_err(&pdev->dev, "failed to get I/O memory\n");
-                goto err;
+                goto err_iomap;
         }
 
         flctl->reg = ioremap(res->start, resource_size(res));
         if (flctl->reg == NULL) {
                 dev_err(&pdev->dev, "failed to remap I/O memory\n");
-                goto err;
+                goto err_iomap;
         }
 
         platform_set_drvdata(pdev, flctl);
@@ -871,23 +898,28 @@ static int __devinit flctl_probe(struct platform_device *pdev)
                 nand->read_word = flctl_read_word;
         }
 
+        pm_runtime_enable(&pdev->dev);
+        pm_runtime_resume(&pdev->dev);
+
         ret = nand_scan_ident(flctl_mtd, 1, NULL);
         if (ret)
-                goto err;
+                goto err_chip;
 
         ret = flctl_chip_init_tail(flctl_mtd);
         if (ret)
-                goto err;
+                goto err_chip;
 
         ret = nand_scan_tail(flctl_mtd);
         if (ret)
-                goto err;
+                goto err_chip;
 
         mtd_device_register(flctl_mtd, pdata->parts, pdata->nr_parts);
 
         return 0;
 
-err:
+err_chip:
+        pm_runtime_disable(&pdev->dev);
+err_iomap:
         kfree(flctl);
         return ret;
 }
@@ -897,6 +929,7 @@ static int __devexit flctl_remove(struct platform_device *pdev)
         struct sh_flctl *flctl = platform_get_drvdata(pdev);
 
         nand_release(&flctl->mtd);
+        pm_runtime_disable(&pdev->dev);
         kfree(flctl);
 
         return 0;
diff --git a/include/linux/mtd/sh_flctl.h b/include/linux/mtd/sh_flctl.h
index 8bcf299cb9bf..a38e1fa8af01 100644
--- a/include/linux/mtd/sh_flctl.h
+++ b/include/linux/mtd/sh_flctl.h
@@ -23,6 +23,7 @@
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/nand.h>
 #include <linux/mtd/partitions.h>
+#include <linux/pm_qos.h>
 
 /* FLCTL registers */
 #define FLCMNCR(f)              (f->reg + 0x0)
@@ -131,6 +132,7 @@ struct sh_flctl {
         struct mtd_info         mtd;
         struct nand_chip        chip;
         struct platform_device  *pdev;
+        struct dev_pm_qos_request pm_qos;
         void __iomem            *reg;
 
         uint8_t done_buff[2048 + 64];   /* max size 2048 + 64 */
@@ -149,6 +151,7 @@ struct sh_flctl {
         unsigned page_size:1;   /* NAND page size (0 = 512, 1 = 2048) */
         unsigned hwecc:1;       /* Hardware ECC (0 = disabled, 1 = enabled) */
         unsigned holden:1;      /* Hardware has FLHOLDCR and HOLDEN is set */
+        unsigned qos_request:1; /* QoS request to prevent deep power shutdown */
 };
 
 struct sh_flctl_platform_data {