scsi: ufs: Add sysfs node to dynamically control clock scaling

Provide an option to enable/disable clock scaling during runtime.
Write 1/0 to "clkscale_enable" sysfs node to enable/disable clock
scaling.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 0da9e16..4468ba0 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -230,6 +230,9 @@ static int ufshcd_uic_hibern8_exit(struct ufs_hba *hba);
 static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba);
 static inline void ufshcd_add_delay_before_dme_cmd(struct ufs_hba *hba);
 static int ufshcd_host_reset_and_restore(struct ufs_hba *hba);
+static void ufshcd_resume_clkscaling(struct ufs_hba *hba);
+static void ufshcd_suspend_clkscaling(struct ufs_hba *hba);
+static int ufshcd_scale_clks(struct ufs_hba *hba, bool scale_up);
 static irqreturn_t ufshcd_intr(int irq, void *__hba);
 static int ufshcd_config_pwr_mode(struct ufs_hba *hba,
                struct ufs_pa_layer_attr *desired_pwr_mode);
@@ -713,16 +716,58 @@ static bool ufshcd_is_unipro_pa_params_tuning_req(struct ufs_hba *hba)
 
 static void ufshcd_suspend_clkscaling(struct ufs_hba *hba)
 {
-       if (ufshcd_is_clkscaling_enabled(hba)) {
-               devfreq_suspend_device(hba->devfreq);
-               hba->clk_scaling.window_start_t = 0;
-       }
+       if (!ufshcd_is_clkscaling_supported(hba))
+               return;
+
+       devfreq_suspend_device(hba->devfreq);
+       hba->clk_scaling.window_start_t = 0;
 }
 
 static void ufshcd_resume_clkscaling(struct ufs_hba *hba)
 {
-       if (ufshcd_is_clkscaling_enabled(hba))
-               devfreq_resume_device(hba->devfreq);
+       devfreq_resume_device(hba->devfreq);
+}
+
+static ssize_t ufshcd_clkscale_enable_show(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct ufs_hba *hba = dev_get_drvdata(dev);
+
+       return snprintf(buf, PAGE_SIZE, "%d\n", hba->clk_scaling.is_allowed);
+}
+
+static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
+               struct device_attribute *attr, const char *buf, size_t count)
+{
+       struct ufs_hba *hba = dev_get_drvdata(dev);
+       u32 value;
+       int err;
+
+       if (kstrtou32(buf, 0, &value))
+               return -EINVAL;
+
+       value = !!value;
+       if (value == hba->clk_scaling.is_allowed)
+               goto out;
+
+       pm_runtime_get_sync(hba->dev);
+       ufshcd_hold(hba, false);
+
+       if (value) {
+               ufshcd_resume_clkscaling(hba);
+       } else {
+               ufshcd_suspend_clkscaling(hba);
+               err = ufshcd_scale_clks(hba, true);
+               if (err)
+                       dev_err(hba->dev, "%s: failed to scale clocks up %d\n",
+                                       __func__, err);
+       }
+       hba->clk_scaling.is_allowed = value;
+
+       ufshcd_release(hba);
+       pm_runtime_put_sync(hba->dev);
+out:
+       return count;
 }
 
 static void ufshcd_ungate_work(struct work_struct *work)
@@ -758,7 +803,8 @@ static void ufshcd_ungate_work(struct work_struct *work)
                hba->clk_gating.is_suspended = false;
        }
 unblock_reqs:
-       ufshcd_resume_clkscaling(hba);
+       if (hba->clk_scaling.is_allowed)
+               ufshcd_resume_clkscaling(hba);
        scsi_unblock_requests(hba->host);
 }
 
@@ -1046,7 +1092,7 @@ static void ufshcd_exit_clk_gating(struct ufs_hba *hba)
 /* Must be called with host lock acquired */
 static void ufshcd_clk_scaling_start_busy(struct ufs_hba *hba)
 {
-       if (!ufshcd_is_clkscaling_enabled(hba))
+       if (!ufshcd_is_clkscaling_supported(hba))
                return;
 
        if (!hba->clk_scaling.is_busy_started) {
@@ -1059,7 +1105,7 @@ static void ufshcd_clk_scaling_update_busy(struct ufs_hba *hba)
 {
        struct ufs_clk_scaling *scaling = &hba->clk_scaling;
 
-       if (!ufshcd_is_clkscaling_enabled(hba))
+       if (!ufshcd_is_clkscaling_supported(hba))
                return;
 
        if (!hba->outstanding_reqs && scaling->is_busy_started) {
@@ -5526,12 +5572,15 @@ static int ufshcd_probe_hba(struct ufs_hba *hba)
                pm_runtime_put_sync(hba->dev);
        }
 
+       /* Resume devfreq after UFS device is detected */
+       if (ufshcd_is_clkscaling_supported(hba)) {
+               ufshcd_resume_clkscaling(hba);
+               hba->clk_scaling.is_allowed = true;
+       }
+
        if (!hba->is_init_prefetch)
                hba->is_init_prefetch = true;
 
-       /* Resume devfreq after UFS device is detected */
-       ufshcd_resume_clkscaling(hba);
-
 out:
        /*
         * If we failed to initialize the device or the device is not
@@ -6484,7 +6533,8 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
        ufshcd_urgent_bkops(hba);
        hba->clk_gating.is_suspended = false;
 
-       ufshcd_resume_clkscaling(hba);
+       if (hba->clk_scaling.is_allowed)
+               ufshcd_resume_clkscaling(hba);
 
        /* Schedule clock gating in case of no access to UFS device yet */
        ufshcd_release(hba);
@@ -6702,6 +6752,8 @@ void ufshcd_remove(struct ufs_hba *hba)
        ufshcd_hba_stop(hba, true);
 
        ufshcd_exit_clk_gating(hba);
+       if (ufshcd_is_clkscaling_supported(hba))
+               device_remove_file(hba->dev, &hba->clk_scaling.enable_attr);
        ufshcd_hba_exit(hba);
 }
 EXPORT_SYMBOL_GPL(ufshcd_remove);
@@ -6835,7 +6887,7 @@ static int ufshcd_devfreq_target(struct device *dev,
        bool release_clk_hold = false;
        unsigned long irq_flags;
 
-       if (!ufshcd_is_clkscaling_enabled(hba))
+       if (!ufshcd_is_clkscaling_supported(hba))
                return -EINVAL;
 
        spin_lock_irqsave(hba->host->host_lock, irq_flags);
@@ -6883,7 +6935,7 @@ static int ufshcd_devfreq_get_dev_status(struct device *dev,
        struct ufs_clk_scaling *scaling = &hba->clk_scaling;
        unsigned long flags;
 
-       if (!ufshcd_is_clkscaling_enabled(hba))
+       if (!ufshcd_is_clkscaling_supported(hba))
                return -EINVAL;
 
        memset(stat, 0, sizeof(*stat));
@@ -6919,6 +6971,16 @@ static struct devfreq_dev_profile ufs_devfreq_profile = {
        .target         = ufshcd_devfreq_target,
        .get_dev_status = ufshcd_devfreq_get_dev_status,
 };
+static void ufshcd_clkscaling_init_sysfs(struct ufs_hba *hba)
+{
+       hba->clk_scaling.enable_attr.show = ufshcd_clkscale_enable_show;
+       hba->clk_scaling.enable_attr.store = ufshcd_clkscale_enable_store;
+       sysfs_attr_init(&hba->clk_scaling.enable_attr.attr);
+       hba->clk_scaling.enable_attr.attr.name = "clkscale_enable";
+       hba->clk_scaling.enable_attr.attr.mode = 0644;
+       if (device_create_file(hba->dev, &hba->clk_scaling.enable_attr))
+               dev_err(hba->dev, "Failed to create sysfs for clkscale_enable\n");
+}
 
 /**
  * ufshcd_init - Driver initialization routine
@@ -7045,7 +7107,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
                goto out_remove_scsi_host;
        }
 
-       if (ufshcd_is_clkscaling_enabled(hba)) {
+       if (ufshcd_is_clkscaling_supported(hba)) {
                hba->devfreq = devm_devfreq_add_device(dev, &ufs_devfreq_profile,
                                                   "simple_ondemand", NULL);
                if (IS_ERR(hba->devfreq)) {
@@ -7056,6 +7118,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
                }
                /* Suspend devfreq until the UFS device is detected */
                ufshcd_suspend_clkscaling(hba);
+               ufshcd_clkscaling_init_sysfs(hba);
        }
 
        /* Hold auto suspend until async scan completes */

diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 0882ba6..bdd2284 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -342,6 +342,8 @@ struct ufs_clk_scaling {
        bool is_busy_started;
        unsigned long  tot_busy_t;
        unsigned long window_start_t;
+       struct device_attribute enable_attr;
+       bool is_allowed;
 };
 
 /**
@@ -580,7 +582,7 @@ static inline bool ufshcd_can_hibern8_during_gating(struct ufs_hba *hba)
 {
        return hba->caps & UFSHCD_CAP_HIBERN8_WITH_CLK_GATING;
 }
-static inline int ufshcd_is_clkscaling_enabled(struct ufs_hba *hba)
+static inline int ufshcd_is_clkscaling_supported(struct ufs_hba *hba)
 {
        return hba->caps & UFSHCD_CAP_CLK_SCALING;
 }