From 014e61878ad7a06497caefd6c7a3b1b6a60a4ae3 Mon Sep 17 00:00:00 2001
From: Yaniv Gardi <ygardi@codeaurora.org>
Date: Wed, 30 Oct 2013 08:38:16 +0200
Subject: [PATCH] scsi: ufs: read the device bRefClkFreq attribute

Device reference clock is a crucial parameter, as
it would fail to work in HS, if its value is different than 19.2 MHz.
This is why we should read its value upon start-up and notify
its value as a debug message.
We don't want to "blindly" configure this attribute as well, as this is
a one-time-programmable parameter and should be considered carefully
before setting it.

Change-Id: Ia2cc0f18fae1189949c30b5b2a65b763c1c46fb1
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 43 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 2737ff3b858d..c402f0116810 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -4413,6 +4413,41 @@ out:
 	return ret;
 }
 
+/**
+ * ufshcd_get_device_ref_clk - get the device bRefClkFreq
+ * @hba: per-adapter instance
+ *
+ * Returns zero on success, non-zero error value on failure.
+ */
+static int ufshcd_get_device_ref_clk(struct ufs_hba *hba)
+{
+	int err = 0;
+	int val = -1;
+	int retries;
+	char *arr[] = {"19.2 MHz", "26 MHz", "38.4 MHz", "52 MHz"};
+
+	for (retries = QUERY_REQ_RETRIES; retries > 0; retries--) {
+		/* write attribute */
+		err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
+			QUERY_ATTR_IDN_REF_CLK_FREQ, 0, 0, &val);
+		if (!err)
+			break;
+
+		dev_dbg(hba->dev, "%s: failed with error %d\n", __func__, err);
+	}
+
+	if (err || val >= sizeof(arr) || val < 0) {
+		dev_err(hba->dev, "%s: err = %d, val = %d",
+			 __func__, err, val);
+		goto out;
+	}
+
+	dev_info(hba->dev, "%s: bRefClkFreq = %s", __func__, arr[val]);
+
+out:
+	return err;
+}
+
 /**
  * ufshcd_probe_hba - probe hba to detect device and initialize
  * @hba: per-adapter instance
@@ -4440,6 +4475,14 @@ static int ufshcd_probe_hba(struct ufs_hba *hba)
 	if (ret)
 		goto out;
 
+	ret = ufshcd_get_device_ref_clk(hba);
+	if (ret) {
+		dev_err(hba->dev,
+			"%s: Failed reading bRefClkFreq attribute\n",
+			__func__);
+		ret = 0;
+	}
+
 	/* UFS device is also active now */
 	ufshcd_set_ufs_dev_active(hba);
 	ufshcd_force_reset_auto_bkops(hba);