Re: [PATCH 16/24] rtc: pm8xxx: add support for nvmem offset

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On 26/01/2023 14:20, Johan Hovold wrote:
On many Qualcomm platforms the PMIC RTC control and time registers are
read-only so that the RTC time can not be updated. Instead an offset
needs be stored in some machine-specific non-volatile memory, which the
driver can take into account.

Add support for storing a 32-bit offset from the Epoch in an nvmem cell
so that the RTC time can be set on such platforms.

Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
---
  drivers/rtc/rtc-pm8xxx.c | 134 +++++++++++++++++++++++++++++++++++----
  1 file changed, 123 insertions(+), 11 deletions(-)

diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
index 922aef0f0241..09816b9f6282 100644
--- a/drivers/rtc/rtc-pm8xxx.c
+++ b/drivers/rtc/rtc-pm8xxx.c
@@ -3,6 +3,7 @@
   */
+static int pm8xxx_rtc_read_nvmem_offset(struct pm8xxx_rtc *rtc_dd)
+{
+	size_t len;
+	void *buf;
+	int rc;
+
+	buf = nvmem_cell_read(rtc_dd->nvmem_cell, &len);
+	if (IS_ERR(buf)) {
+		rc = PTR_ERR(buf);
+		dev_err(rtc_dd->dev, "failed to read nvmem offset: %d\n", rc);
+		return rc;
+	}
+
+	if (len != sizeof(u32)) {
+		dev_err(rtc_dd->dev, "unexpected nvmem cell size %zu\n", len);
+		kfree(buf);
+		return -EINVAL;
+	}
how about us nvmem_cell_read_u32()

+
+	rtc_dd->offset = get_unaligned_le32(buf);
+
+	kfree(buf);
+
+	return 0;
+}
+



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