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Fri, 19 Dec 2025 13:10:52 +0100 (CET) From: Fredrik M Olsson Date: Fri, 19 Dec 2025 13:10:37 +0100 Subject: [PATCH 3/4] rtc: ds1307: Add Driver for Epson RX8901CE 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: <20251219-ds1307-rx8901-add-v1-3-b13f346ebe93@axis.com> References: <20251219-ds1307-rx8901-add-v1-0-b13f346ebe93@axis.com> In-Reply-To: <20251219-ds1307-rx8901-add-v1-0-b13f346ebe93@axis.com> To: Alexandre Belloni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Nobuhiro Iwamatsu CC: , , , Fredrik M Olsson , X-Mailer: b4 0.13.0 X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: AMS0EPF00000199:EE_|PAWPR02MB10238:EE_ X-MS-Office365-Filtering-Correlation-Id: 5d0ece55-a366-4136-7195-08de3ef7a89d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|82310400026|36860700013|1800799024; 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X-OriginatorOrg: axis.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Dec 2025 12:10:53.9506 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5d0ece55-a366-4136-7195-08de3ef7a89d X-MS-Exchange-CrossTenant-Id: 78703d3c-b907-432f-b066-88f7af9ca3af X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=78703d3c-b907-432f-b066-88f7af9ca3af;Ip=[195.60.68.100];Helo=[mail.axis.com] X-MS-Exchange-CrossTenant-AuthSource: AMS0EPF00000199.eurprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PAWPR02MB10238 Adds Support for: - Reading and writing time to/from the RTC. - Switching to backup battery supply when primary supply disappears. - Optionally enabling battery charging. Signed-off-by: Fredrik M Olsson --- drivers/rtc/rtc-ds1307.c | 62 ++++++++++++++++++++++++++++++++++++++++++++= ++-- 1 file changed, 60 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index bf42c250ea7d..99d95e520108 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -48,6 +48,7 @@ enum ds_type { mcp794xx, rx_8025, rx_8130, + rx_8901, last_ds_type /* always last */ /* rs5c372 too? different address... */ }; @@ -129,6 +130,12 @@ enum ds_type { #define RX8130_REG_CONTROL1_INIEN BIT(4) #define RX8130_REG_CONTROL1_CHGEN BIT(5) =20 +#define RX8901_REG_INTF 0x0e +#define RX8901_REG_INTF_VLF BIT(1) +#define RX8901_REG_PWSW_CFG 0x37 +#define RX8901_REG_PWSW_CFG_INIEN BIT(6) +#define RX8901_REG_PWSW_CFG_CHGEN BIT(7) + #define MCP794XX_REG_CONTROL 0x07 # define MCP794XX_BIT_ALM0_EN 0x10 # define MCP794XX_BIT_ALM1_EN 0x20 @@ -226,6 +233,19 @@ static int ds1307_get_time(struct device *dev, struct = rtc_time *t) dev_warn_once(dev, "oscillator failed, set time!\n"); return -EINVAL; } + } else if (ds1307->type =3D=3D rx_8901) { + unsigned int regflag; + + ret =3D regmap_read(ds1307->regmap, RX8901_REG_INTF, ®flag); + if (ret) { + dev_err(dev, "%s error %d\n", "read", ret); + return ret; + } + + if (regflag & RX8901_REG_INTF_VLF) { + dev_warn_once(dev, "oscillator failed, set time!\n"); + return -EINVAL; + } } =20 /* read the RTC date and time registers all at once */ @@ -307,7 +327,7 @@ static int ds1307_get_time(struct device *dev, struct r= tc_time *t) tmp =3D regs[DS1307_REG_HOUR] & 0x3f; t->tm_hour =3D bcd2bin(tmp); /* rx8130 is bit position, not BCD */ - if (ds1307->type =3D=3D rx_8130) + if (ds1307->type =3D=3D rx_8130 || ds1307->type =3D=3D rx_8901) t->tm_wday =3D fls(regs[DS1307_REG_WDAY] & 0x7f) - 1; else t->tm_wday =3D bcd2bin(regs[DS1307_REG_WDAY] & 0x07) - 1; @@ -358,7 +378,7 @@ static int ds1307_set_time(struct device *dev, struct r= tc_time *t) regs[DS1307_REG_MIN] =3D bin2bcd(t->tm_min); regs[DS1307_REG_HOUR] =3D bin2bcd(t->tm_hour); /* rx8130 is bit position, not BCD */ - if (ds1307->type =3D=3D rx_8130) + if (ds1307->type =3D=3D rx_8130 || ds1307->type =3D=3D rx_8901) regs[DS1307_REG_WDAY] =3D 1 << t->tm_wday; else regs[DS1307_REG_WDAY] =3D bin2bcd(t->tm_wday + 1); @@ -422,6 +442,17 @@ static int ds1307_set_time(struct device *dev, struct = rtc_time *t) dev_err(dev, "%s error %d\n", "write", result); return result; } + } else if (ds1307->type =3D=3D rx_8901) { + /* + * clear Voltage Loss Flag as data is available now (writing 1 + * to the other bits in the INTF register has no effect) + */ + result =3D regmap_write(ds1307->regmap, RX8901_REG_INTF, + 0xff ^ RX8901_REG_INTF_VLF); + if (result) { + dev_err(dev, "%s error %d\n", "write", result); + return result; + } } =20 return 0; @@ -568,6 +599,17 @@ static u8 do_trickle_setup_rx8130(struct ds1307 *ds130= 7, u32 ohms, bool diode) return setup; } =20 +static u8 do_trickle_setup_rx8901(struct ds1307 *ds1307, u32 ohms, bool di= ode) +{ + /* make sure that the backup battery is enabled */ + u8 setup =3D RX8901_REG_PWSW_CFG_INIEN; + + if (diode) + setup |=3D RX8901_REG_PWSW_CFG_CHGEN; + + return setup; +} + static irqreturn_t rx8130_irq(int irq, void *dev_id) { struct ds1307 *ds1307 =3D dev_id; @@ -960,6 +1002,11 @@ static const struct rtc_class_ops rx8130_rtc_ops =3D { .alarm_irq_enable =3D rx8130_alarm_irq_enable, }; =20 +static const struct rtc_class_ops rx8901_rtc_ops =3D { + .read_time =3D ds1307_get_time, + .set_time =3D ds1307_set_time, +}; + static const struct rtc_class_ops mcp794xx_rtc_ops =3D { .read_time =3D ds1307_get_time, .set_time =3D ds1307_set_time, @@ -1040,6 +1087,12 @@ static const struct chip_desc chips[last_ds_type] = =3D { .trickle_charger_reg =3D RX8130_REG_CONTROL1, .do_trickle_setup =3D &do_trickle_setup_rx8130, }, + [rx_8901] =3D { + .offset =3D 0x0, + .rtc_ops =3D &rx8901_rtc_ops, + .trickle_charger_reg =3D RX8901_REG_PWSW_CFG, + .do_trickle_setup =3D &do_trickle_setup_rx8901, + }, [m41t0] =3D { .rtc_ops =3D &m41txx_rtc_ops, }, @@ -1081,6 +1134,7 @@ static const struct i2c_device_id ds1307_id[] =3D { { "rx8025", rx_8025 }, { "isl12057", ds_1337 }, { "rx8130", rx_8130 }, + { "rx8901", rx_8901 }, { } }; MODULE_DEVICE_TABLE(i2c, ds1307_id); @@ -1158,6 +1212,10 @@ static const struct of_device_id ds1307_of_match[] = =3D { .compatible =3D "epson,rx8130", .data =3D (void *)rx_8130 }, + { + .compatible =3D "epson,rx8901", + .data =3D (void *)rx_8901 + }, { } }; MODULE_DEVICE_TABLE(of, ds1307_of_match); --=20 2.43.0