Date:   Sat, 7 May 2022 12:57:30 +0800
From:   Po-Wen Kao <powen.kao@...iatek.com>
To:     <j-young.choi@...sung.com>, Alim Akhtar <alim.akhtar@...sung.com>,
        "Avri Altman" <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>
CC:     <wsd_upstream@...iatek.com>, <peter.wang@...iatek.com>,
        <stanley.chu@...iatek.com>, <powen.kao@...iatek.com>,
        <alice.chao@...iatek.com>, <chun-hung.wu@...iatek.com>,
        <cc.chou@...iatek.com>, <chaotian.jing@...iatek.com>,
        <jiajie.hao@...iatek.com>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: [PATCH v2] scsi: ufs: add clock-scalable property for clk scaling

In clk scaling, clk_set_rate is invoked to set dedicated PLL clk rate
on scale up and down. On some MTK platform, scaling is only possible
by switching parent of a mux, therefore we introduce a new
"clock-scalable" property to gain fine control over which clock rate can
be scaled by calling clk_set_rate. If a clock is defined as non-scalable,
clk_set_rate won't be invoked while clki->current_rate is still updated
if min/max freq is defined. Customized clk operation may be embedded in
pre/post change of hba->vops->clk_scale_notify.

All clocks in dts without "clock-scalable" property defined are assumed
scalable and works as usual. There is no neeed to make change on existing
dts.

To specify scalable property, one may define dts as follow

&ufshci {
    clocks =
        <clk1>,
        <clk2>,
        ...
        <clkn>;

    clock-names =
        "clk1",
        "clk2",
        ...
        "clkn";

    freq-table-hz =
        <1000 2000>,
        <0 0>,
        ...
        <0 0>;

    clock-scalable =
        <0
         0
         ...
         0
        >;
};

Signed-off-by: Po-Wen Kao <powen.kao@...iatek.com>
---
 drivers/scsi/ufs/ufshcd-pltfrm.c | 96 +++++++++++++++++++++++---------
 drivers/scsi/ufs/ufshcd.c        | 54 +++++++-----------
 drivers/scsi/ufs/ufshcd.h        |  2 +
 include/trace/events/ufs.h       | 16 +++---
 4 files changed, 102 insertions(+), 66 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
index 87975d1a21c8..5f95bb519485 100644
--- a/drivers/scsi/ufs/ufshcd-pltfrm.c
+++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
@@ -18,6 +18,56 @@
 
 #define UFSHCD_DEFAULT_LANES_PER_DIRECTION		2
 
+/**
+ * ufshcd_get_clk_u32_array - Resolve property in dts to u32 array with
+ * shape check.
+ * @hba: per-adapter instance
+ * @propname: name of property
+ * @cols: column count
+ * @rows: calculated row count with given cols
+ * @array: u32 array pointer of property data with propname
+ */
+static int ufshcd_get_clk_u32_array(struct ufs_hba *hba, const char *propname,
+				    size_t cols, size_t *rows, u32 **array)
+{
+	struct device *dev = hba->dev;
+	struct device_node *np = dev->of_node;
+	int len = 0, ret = 0;
+	int _rows = 0;
+
+	if (!of_get_property(np, propname, &len)) {
+		dev_warn(dev, "%s property not specified.\n", propname);
+		return -EINVAL;
+	}
+
+	len = len / sizeof(**array);
+	if (!cols || !len || len % cols != 0) {
+		dev_warn(dev, "%s property define error.\n", propname);
+		return -EINVAL;
+	}
+	_rows = len / cols;
+
+	*array = devm_kcalloc(dev, len, sizeof(**array), GFP_KERNEL);
+	if (!*array) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = of_property_read_u32_array(np, propname, *array, len);
+	if (ret) {
+		dev_err(dev, "%s: error reading array %d\n",
+			propname, ret);
+		goto out;
+	}
+
+	*rows = _rows;
+
+	return 0;
+out:
+	devm_kfree(dev, *array);
+	return ret;
+}
+
 static int ufshcd_parse_clock_info(struct ufs_hba *hba)
 {
 	int ret = 0;
@@ -27,13 +77,14 @@ static int ufshcd_parse_clock_info(struct ufs_hba *hba)
 	struct device_node *np = dev->of_node;
 	char *name;
 	u32 *clkfreq = NULL;
+	u32 *scalable = NULL;
 	struct ufs_clk_info *clki;
-	int len = 0;
 	size_t sz = 0;
 
 	if (!np)
 		goto out;
 
+	/* clock-names */
 	cnt = of_property_count_strings(np, "clock-names");
 	if (!cnt || (cnt == -EINVAL)) {
 		dev_info(dev, "%s: Unable to find clocks, assuming enabled\n",
@@ -47,37 +98,29 @@ static int ufshcd_parse_clock_info(struct ufs_hba *hba)
 	if (cnt <= 0)
 		goto out;
 
-	if (!of_get_property(np, "freq-table-hz", &len)) {
-		dev_info(dev, "freq-table-hz property not specified\n");
+	/* clock-scalable (optional) */
+	ret = ufshcd_get_clk_u32_array(hba, "clock-scalable", 1, &sz, &scalable);
+	if (ret) {
+		dev_warn(dev, "Optional property %s load failed. Assume all clocks scalable.\n",
+			 "clock-scalable");
+	} else if (sz != cnt) {
+		dev_err(dev, "%s len mismatch\n", "clock-scalable");
+		ret = -EINVAL;
 		goto out;
 	}
 
-	if (len <= 0)
+	/* freq-table-hz */
+	ret = ufshcd_get_clk_u32_array(hba, "freq-table-hz", 2, &sz, &clkfreq);
+	if (ret) {
+		dev_err(dev, "Property %s load failed.", "freq-table-hz");
 		goto out;
-
-	sz = len / sizeof(*clkfreq);
-	if (sz != 2 * cnt) {
+	} else if (sz != cnt) {
 		dev_err(dev, "%s len mismatch\n", "freq-table-hz");
 		ret = -EINVAL;
 		goto out;
 	}
 
-	clkfreq = devm_kcalloc(dev, sz, sizeof(*clkfreq),
-			       GFP_KERNEL);
-	if (!clkfreq) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	ret = of_property_read_u32_array(np, "freq-table-hz",
-			clkfreq, sz);
-	if (ret && (ret != -EINVAL)) {
-		dev_err(dev, "%s: error reading array %d\n",
-				"freq-table-hz", ret);
-		return ret;
-	}
-
-	for (i = 0; i < sz; i += 2) {
+	for (i = 0; i < cnt * 2; i += 2) {
 		ret = of_property_read_string_index(np,
 				"clock-names", i/2, (const char **)&name);
 		if (ret)
@@ -92,6 +135,7 @@ static int ufshcd_parse_clock_info(struct ufs_hba *hba)
 		clki->min_freq = clkfreq[i];
 		clki->max_freq = clkfreq[i+1];
 		clki->name = devm_kstrdup(dev, name, GFP_KERNEL);
+		clki->scalable = scalable ? !!scalable[i / 2] : true;
 		if (!clki->name) {
 			ret = -ENOMEM;
 			goto out;
@@ -99,11 +143,13 @@ static int ufshcd_parse_clock_info(struct ufs_hba *hba)
 
 		if (!strcmp(name, "ref_clk"))
 			clki->keep_link_active = true;
-		dev_dbg(dev, "%s: min %u max %u name %s\n", "freq-table-hz",
-				clki->min_freq, clki->max_freq, clki->name);
+		dev_dbg(dev, "clk %s: scalable(%u), min(%u), max(%u)\n",
+			clki->name, clki->scalable, clki->min_freq, clki->max_freq);
 		list_add_tail(&clki->list, &hba->clk_list_head);
 	}
 out:
+	devm_kfree(dev, scalable);
+	devm_kfree(dev, clkfreq);
 	return ret;
 }
 
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index eea5af5fa166..8dbae2f73329 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -939,6 +939,11 @@ static bool ufshcd_is_unipro_pa_params_tuning_req(struct ufs_hba *hba)
 		return false;
 }
 
+static inline int ufshcd_clk_set_rate(struct ufs_clk_info *clki, unsigned long rate)
+{
+	return clki->scalable ? clk_set_rate(clki->clk, rate) : 0;
+}
+
 /**
  * ufshcd_set_clk_freq - set UFS controller clock frequencies
  * @hba: per adapter instance
@@ -950,6 +955,7 @@ static bool ufshcd_is_unipro_pa_params_tuning_req(struct ufs_hba *hba)
 static int ufshcd_set_clk_freq(struct ufs_hba *hba, bool scale_up)
 {
 	int ret = 0;
+	u32 target_rate = 0;
 	struct ufs_clk_info *clki;
 	struct list_head *head = &hba->clk_list_head;
 
@@ -958,41 +964,23 @@ static int ufshcd_set_clk_freq(struct ufs_hba *hba, bool scale_up)
 
 	list_for_each_entry(clki, head, list) {
 		if (!IS_ERR_OR_NULL(clki->clk)) {
-			if (scale_up && clki->max_freq) {
-				if (clki->curr_freq == clki->max_freq)
-					continue;
-
-				ret = clk_set_rate(clki->clk, clki->max_freq);
-				if (ret) {
-					dev_err(hba->dev, "%s: %s clk set rate(%dHz) failed, %d\n",
-						__func__, clki->name,
-						clki->max_freq, ret);
-					break;
-				}
-				trace_ufshcd_clk_scaling(dev_name(hba->dev),
-						"scaled up", clki->name,
-						clki->curr_freq,
-						clki->max_freq);
-
-				clki->curr_freq = clki->max_freq;
+			target_rate = scale_up ? clki->max_freq : clki->min_freq;
 
-			} else if (!scale_up && clki->min_freq) {
-				if (clki->curr_freq == clki->min_freq)
-					continue;
+			if (!target_rate || clki->curr_freq == target_rate)
+				continue;
 
-				ret = clk_set_rate(clki->clk, clki->min_freq);
-				if (ret) {
-					dev_err(hba->dev, "%s: %s clk set rate(%dHz) failed, %d\n",
-						__func__, clki->name,
-						clki->min_freq, ret);
-					break;
-				}
-				trace_ufshcd_clk_scaling(dev_name(hba->dev),
-						"scaled down", clki->name,
-						clki->curr_freq,
-						clki->min_freq);
-				clki->curr_freq = clki->min_freq;
+			ret = ufshcd_clk_set_rate(clki, target_rate);
+			if (ret) {
+				dev_err(hba->dev, "%s: %s clk set rate(%dHz) failed, %d\n",
+					__func__, clki->name,
+					target_rate, ret);
+				break;
 			}
+			trace_ufshcd_clk_scaling(dev_name(hba->dev),
+						 clki->name, scale_up,
+						 clki->curr_freq,
+						 target_rate);
+			clki->curr_freq = target_rate;
 		}
 		dev_dbg(hba->dev, "%s: clk: %s, rate: %lu\n", __func__,
 				clki->name, clk_get_rate(clki->clk));
@@ -8364,7 +8352,7 @@ static int ufshcd_init_clocks(struct ufs_hba *hba)
 			ufshcd_parse_dev_ref_clk_freq(hba, clki->clk);
 
 		if (clki->max_freq) {
-			ret = clk_set_rate(clki->clk, clki->max_freq);
+			ret = ufshcd_clk_set_rate(clki, clki->max_freq);
 			if (ret) {
 				dev_err(hba->dev, "%s: %s clk set rate(%dHz) failed, %d\n",
 					__func__, clki->name,
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 1637f5cc1420..eaa3d6c5b9ab 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -260,6 +260,7 @@ struct ufs_dev_cmd {
  * @keep_link_active: indicates that the clk should not be disabled if
 		      link is active
  * @enabled: variable to check against multiple enable/disable
+ * @scalable: indicates if clk is scalable in clk scaling
  */
 struct ufs_clk_info {
 	struct list_head list;
@@ -270,6 +271,7 @@ struct ufs_clk_info {
 	u32 curr_freq;
 	bool keep_link_active;
 	bool enabled;
+	bool scalable;
 };
 
 enum ufs_notify_change_status {
diff --git a/include/trace/events/ufs.h b/include/trace/events/ufs.h
index 599739ee7b20..780c964e52c2 100644
--- a/include/trace/events/ufs.h
+++ b/include/trace/events/ufs.h
@@ -103,30 +103,30 @@ TRACE_EVENT(ufshcd_clk_gating,
 
 TRACE_EVENT(ufshcd_clk_scaling,
 
-	TP_PROTO(const char *dev_name, const char *state, const char *clk,
-		u32 prev_state, u32 curr_state),
+	TP_PROTO(const char *dev_name, const char *clk,
+		 bool up, u32 prev_state, u32 curr_state),
 
-	TP_ARGS(dev_name, state, clk, prev_state, curr_state),
+	TP_ARGS(dev_name, clk, up, prev_state, curr_state),
 
 	TP_STRUCT__entry(
 		__string(dev_name, dev_name)
-		__string(state, state)
 		__string(clk, clk)
+		__field(bool, up)
 		__field(u32, prev_state)
 		__field(u32, curr_state)
 	),
 
 	TP_fast_assign(
 		__assign_str(dev_name, dev_name);
-		__assign_str(state, state);
 		__assign_str(clk, clk);
+		__entry->up = up;
 		__entry->prev_state = prev_state;
 		__entry->curr_state = curr_state;
 	),
 
-	TP_printk("%s: %s %s from %u to %u Hz",
-		__get_str(dev_name), __get_str(state), __get_str(clk),
-		__entry->prev_state, __entry->curr_state)
+	TP_printk("%s: scaled %s %s from %u to %u Hz",
+		  __get_str(dev_name), __entry->up ? "up" : "down", __get_str(clk),
+		  __entry->prev_state, __entry->curr_state)
 );
 
 TRACE_EVENT(ufshcd_auto_bkops_state,
-- 
2.18.0

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