[PATCH v1 2/2] scsi: ufs: Support reading UFS's Vcc voltage from device tree

Bao D. Nguyen
2020-09-01T06:01:34Z

The UFS specifications supports a range of Vcc operating voltage
from 2.4-3.6V depending on the device and manufacturers.
Allows selecting the UFS Vcc voltage level by setting the
UFS's entry vcc-voltage-level in the device tree. If UFS's
vcc-voltage-level setting is not found in the device tree,
use default values provided by the driver.

Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Bao D. Nguyen <nguyenb@codeaurora.org>
---
drivers/scsi/ufs/ufshcd-pltfrm.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
index 3db0af6..48f429c 100644
--- a/drivers/scsi/ufs/ufshcd-pltfrm.c
+++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
@@ -104,10 +104,11 @@ static int ufshcd_parse_clock_info(struct ufs_hba *hba)
static int ufshcd_populate_vreg(struct device *dev, const char *name,
struct ufs_vreg **out_vreg)
{
- int ret = 0;
+ int len, ret = 0;
char prop_name[MAX_PROP_SIZE];
struct ufs_vreg *vreg = NULL;
struct device_node *np = dev->of_node;
+ const __be32 *prop;

if (!np) {
dev_err(dev, "%s: non DT initialization\n", __func__);
@@ -138,8 +139,16 @@ static int ufshcd_populate_vreg(struct device *dev, const char *name,
vreg->min_uV = UFS_VREG_VCC_1P8_MIN_UV;
vreg->max_uV = UFS_VREG_VCC_1P8_MAX_UV;
} else {
- vreg->min_uV = UFS_VREG_VCC_MIN_UV;
- vreg->max_uV = UFS_VREG_VCC_MAX_UV;
+ prop = of_get_property(np, "vcc-voltage-level", &len);
+ if (!prop || (len != (2 * sizeof(__be32)))) {
+ dev_warn(dev, "%s vcc-voltage-level property.\n",
+ prop ? "invalid format" : "no");
+ vreg->min_uV = UFS_VREG_VCC_MIN_UV;
+ vreg->max_uV = UFS_VREG_VCC_MAX_UV;
+ } else {
+ vreg->min_uV = be32_to_cpup(&prop[0]);
+ vreg->max_uV = be32_to_cpup(&prop[1]);
+ }
}
} else if (!strcmp(name, "vccq")) {
vreg->min_uV = UFS_VREG_VCCQ_MIN_UV;
--
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