scsi: ufs: sysfs: Make max_number_of_rtt read-write

Given the importance of the RTT parameter, we want to be able to configure
it via sysfs. This is because UFS users should be discouraged from change
UFS device parameters without the UFSHCI driver being aware of these
changes.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
Link: https://lore.kernel.org/r/20240530142510.734-4-avri.altman@wdc.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 72 insertions, 1 deletions

diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
index 3d049967f6bc..e80a32421a8c 100644
--- a/drivers/ufs/core/ufs-sysfs.c
+++ b/drivers/ufs/core/ufs-sysfs.c
@@ -1340,6 +1340,78 @@ static const struct attribute_group ufs_sysfs_flags_group = {
 	.attrs = ufs_sysfs_device_flags,
 };
 
+static ssize_t max_number_of_rtt_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+	u32 rtt;
+	int ret;
+
+	down(&hba->host_sem);
+	if (!ufshcd_is_user_access_allowed(hba)) {
+		up(&hba->host_sem);
+		return -EBUSY;
+	}
+
+	ufshcd_rpm_get_sync(hba);
+	ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
+		QUERY_ATTR_IDN_MAX_NUM_OF_RTT, 0, 0, &rtt);
+	ufshcd_rpm_put_sync(hba);
+
+	if (ret)
+		goto out;
+
+	ret = sysfs_emit(buf, "0x%08X\n", rtt);
+
+out:
+	up(&hba->host_sem);
+	return ret;
+}
+
+static ssize_t max_number_of_rtt_store(struct device *dev,
+				       struct device_attribute *attr,
+				       const char *buf, size_t count)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+	struct ufs_dev_info *dev_info = &hba->dev_info;
+	struct scsi_device *sdev;
+	unsigned int rtt;
+	int ret;
+
+	if (kstrtouint(buf, 0, &rtt))
+		return -EINVAL;
+
+	if (rtt > dev_info->rtt_cap) {
+		dev_err(dev, "rtt can be at most bDeviceRTTCap\n");
+		return -EINVAL;
+	}
+
+	down(&hba->host_sem);
+	if (!ufshcd_is_user_access_allowed(hba)) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	ufshcd_rpm_get_sync(hba);
+
+	shost_for_each_device(sdev, hba->host)
+		blk_mq_freeze_queue(sdev->request_queue);
+
+	ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
+		QUERY_ATTR_IDN_MAX_NUM_OF_RTT, 0, 0, &rtt);
+
+	shost_for_each_device(sdev, hba->host)
+		blk_mq_unfreeze_queue(sdev->request_queue);
+
+	ufshcd_rpm_put_sync(hba);
+
+out:
+	up(&hba->host_sem);
+	return ret < 0 ? ret : count;
+}
+
+static DEVICE_ATTR_RW(max_number_of_rtt);
+
 static inline bool ufshcd_is_wb_attrs(enum attr_idn idn)
 {
 	return idn >= QUERY_ATTR_IDN_WB_FLUSH_STATUS &&
@@ -1387,7 +1459,6 @@ UFS_ATTRIBUTE(max_data_in_size, _MAX_DATA_IN);
 UFS_ATTRIBUTE(max_data_out_size, _MAX_DATA_OUT);
 UFS_ATTRIBUTE(reference_clock_frequency, _REF_CLK_FREQ);
 UFS_ATTRIBUTE(configuration_descriptor_lock, _CONF_DESC_LOCK);
-UFS_ATTRIBUTE(max_number_of_rtt, _MAX_NUM_OF_RTT);
 UFS_ATTRIBUTE(exception_event_control, _EE_CONTROL);
 UFS_ATTRIBUTE(exception_event_status, _EE_STATUS);
 UFS_ATTRIBUTE(ffu_status, _FFU_STATUS);