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Wed, 02 Apr 2025 03:51:22 -0700 (PDT) From: Alexandre Mergnat Date: Wed, 02 Apr 2025 12:51:00 +0200 Subject: [PATCH v2 2/2] rtc: mt6397: Fix mt6357 RTC year offset handling for hwclock commands Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250109-enable-rtc-v2-2-d7ddc3e73c57@baylibre.com> References: <20250109-enable-rtc-v2-0-d7ddc3e73c57@baylibre.com> In-Reply-To: <20250109-enable-rtc-v2-0-d7ddc3e73c57@baylibre.com> To: Eddie Huang , Sean Wang , Alexandre Belloni , Matthias Brugger , AngeloGioacchino Del Regno , Macpaul Lin Cc: linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org, Alexandre Mergnat X-Mailer: b4 0.12.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3525; i=amergnat@baylibre.com; h=from:subject:message-id; bh=UlOHaAsiVzggi6F3jr2SNdC4VdtkMhUHdURJ6+cg8Ac=; b=owEBbQKS/ZANAwAKAStGSZ1+MdRFAcsmYgBn7Rak9MG2ZQ9wzFG+COaaFPM1OY7zFQL8XoFY8klb RxD+gCmJAjMEAAEKAB0WIQQjG17X8+qqcA5g/osrRkmdfjHURQUCZ+0WpAAKCRArRkmdfjHURdTBD/ 9kUNtbI+e7So11TmUK3hsKh9djqbup6vkAx8Pq68W4fj/BeAMNMd7T9IP5jFDOwwx4PykLAxN6JV6k WDxPv/TQp27p8s4T3Bt+Ofre6hh+YAC1yYvJeNx+8cY5xGEQlSj7eIU5yOYz//M83I6OKVJXNPM+He AC/z0hj9Gx6AT3DGH3xCNHZKLPY97mqcg7cOxK24/ZszybgGmHBxG7HID+XO+QonhUBRRt9OeSmz31 CZuMipCh20FBQcLYz3n+JFMEQMbaCOkWXSaiBtziSjBXM9CV7l2KKSkkGL26T8RE77rMh+bf+VCcI8 SVoEB8xItBDQK1HJmd8DwjjK+UqV9EK0VLm1uwtDOH+IWZmzYXKcXexfPLHc9oHcjLxebstsfM7etp qS9Byx0psLWQbS2cgGDhD3EaTF074h5uHg4CyTA24CYE7E5AfxeaPB1eLgyeVsXTZf+DuJPEzowVw9 cZj4Y0zmqEPte46Vbq+2ELMEDZYpDL4yNSVHVYJjoMB9nPvdCPfKIUFxTiDQmR0tl8z6NyZq3Ozz4d m8EV1ehPtjgAPlX4gwTN0RolroIOhAFs9mfYsYxzPO3kYn4kMZTSX6HwJIlQXrsz/0Rjm5zppB0a1q +701CD3lM+r7hRswQPjXMMpuzB7mmerc7tQgEGAiydtikIs0A46CFJ9mgv5g== X-Developer-Key: i=amergnat@baylibre.com; a=openpgp; fpr=231B5ED7F3EAAA700E60FE8B2B46499D7E31D445 The mt6357 RTC was failing when using the `hwclock -r --verbose` command, despite reading correctly through sysfs. There is high chance for other platform to be impacted by the year offset handling issue. The hardware RTC registers store years relative to 1968, but the driver wasn't consistently applying the offset when converting between hardware and Linux time representation. This inconsistency caused alarm rollover failures during device registration, with the error "alarm rollover not handled -22" in the logs, causing hwclock commands to fail. The ioctl interface used by the hwclock command requires proper time range validation that wasn't happening with the inconsistent year offsets. Fixes the issue by applying the year offset in all operations: - Adding (RTC_MIN_YEAR - RTC_BASE_YEAR) when reading from hardware - Subtracting the same offset when writing to hardware - Using the same logic for both regular time and alarm operations With these changes, the hwclock command works correctly and time values are consistently handled across all interfaces. Signed-off-by: Alexandre Mergnat --- drivers/rtc/rtc-mt6397.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/rtc/rtc-mt6397.c b/drivers/rtc/rtc-mt6397.c index 692c00ff544b2..ba52e225dc8fa 100644 --- a/drivers/rtc/rtc-mt6397.c +++ b/drivers/rtc/rtc-mt6397.c @@ -77,7 +77,8 @@ static int __mtk_rtc_read_time(struct mt6397_rtc *rtc, tm->tm_mday =3D data[RTC_OFFSET_DOM]; tm->tm_wday =3D data[RTC_OFFSET_DOW]; tm->tm_mon =3D data[RTC_OFFSET_MTH] & RTC_TC_MTH_MASK; - tm->tm_year =3D data[RTC_OFFSET_YEAR]; + /* The RTC registers store years since 1968 (hardware's base year) */ + tm->tm_year =3D data[RTC_OFFSET_YEAR] + (RTC_MIN_YEAR - RTC_BASE_YEAR); =20 ret =3D regmap_read(rtc->regmap, rtc->addr_base + RTC_TC_SEC, sec); exit: @@ -119,7 +120,8 @@ static int mtk_rtc_set_time(struct device *dev, struct = rtc_time *tm) data[RTC_OFFSET_DOM] =3D tm->tm_mday; data[RTC_OFFSET_DOW] =3D tm->tm_wday; data[RTC_OFFSET_MTH] =3D tm->tm_mon; - data[RTC_OFFSET_YEAR] =3D tm->tm_year; + /* Convert from tm_year (years since 1900) to RTC register format (years = since 1968) */ + data[RTC_OFFSET_YEAR] =3D tm->tm_year - (RTC_MIN_YEAR - RTC_BASE_YEAR); =20 mutex_lock(&rtc->lock); ret =3D regmap_bulk_write(rtc->regmap, rtc->addr_base + RTC_TC_SEC, @@ -165,8 +167,8 @@ static int mtk_rtc_read_alarm(struct device *dev, struc= t rtc_wkalrm *alm) tm->tm_hour =3D data[RTC_OFFSET_HOUR] & RTC_AL_HOU_MASK; tm->tm_mday =3D data[RTC_OFFSET_DOM] & RTC_AL_DOM_MASK; tm->tm_mon =3D data[RTC_OFFSET_MTH] & RTC_AL_MTH_MASK; - tm->tm_year =3D data[RTC_OFFSET_YEAR] & RTC_AL_YEA_MASK; - + /* Apply the same offset conversion for alarm read */ + tm->tm_year =3D (data[RTC_OFFSET_YEAR] & RTC_AL_YEA_MASK) + (RTC_MIN_YEAR= - RTC_BASE_YEAR); tm->tm_mon--; =20 return 0; @@ -200,8 +202,9 @@ static int mtk_rtc_set_alarm(struct device *dev, struct= rtc_wkalrm *alm) (tm->tm_mday & RTC_AL_DOM_MASK)); data[RTC_OFFSET_MTH] =3D ((data[RTC_OFFSET_MTH] & ~(RTC_AL_MTH_MASK)) | (tm->tm_mon & RTC_AL_MTH_MASK)); + /* Convert alarm year using the same offset as in read/write time */ data[RTC_OFFSET_YEAR] =3D ((data[RTC_OFFSET_YEAR] & ~(RTC_AL_YEA_MASK)) | - (tm->tm_year & RTC_AL_YEA_MASK)); + ((tm->tm_year - (RTC_MIN_YEAR - RTC_BASE_YEAR)) & RTC_AL_YEA_MASK)); =20 if (alm->enabled) { ret =3D regmap_bulk_write(rtc->regmap, --=20 2.25.1