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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /drivers/rtc/rtc-m41t94.c
downloadlinux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz
linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
Diffstat (limited to 'drivers/rtc/rtc-m41t94.c')
-rw-r--r--drivers/rtc/rtc-m41t94.c145
1 files changed, 145 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-m41t94.c b/drivers/rtc/rtc-m41t94.c
new file mode 100644
index 000000000..6803b0273
--- /dev/null
+++ b/drivers/rtc/rtc-m41t94.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for ST M41T94 SPI RTC
+ *
+ * Copyright (C) 2008 Kim B. Heino
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+
+#define M41T94_REG_SECONDS 0x01
+#define M41T94_REG_MINUTES 0x02
+#define M41T94_REG_HOURS 0x03
+#define M41T94_REG_WDAY 0x04
+#define M41T94_REG_DAY 0x05
+#define M41T94_REG_MONTH 0x06
+#define M41T94_REG_YEAR 0x07
+#define M41T94_REG_HT 0x0c
+
+#define M41T94_BIT_HALT 0x40
+#define M41T94_BIT_STOP 0x80
+#define M41T94_BIT_CB 0x40
+#define M41T94_BIT_CEB 0x80
+
+static int m41t94_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct spi_device *spi = to_spi_device(dev);
+ u8 buf[8]; /* write cmd + 7 registers */
+
+ dev_dbg(dev, "%s secs=%d, mins=%d, "
+ "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
+ "write", tm->tm_sec, tm->tm_min,
+ tm->tm_hour, tm->tm_mday,
+ tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+ buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
+ buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
+ buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);
+ buf[M41T94_REG_HOURS] = bin2bcd(tm->tm_hour);
+ buf[M41T94_REG_WDAY] = bin2bcd(tm->tm_wday + 1);
+ buf[M41T94_REG_DAY] = bin2bcd(tm->tm_mday);
+ buf[M41T94_REG_MONTH] = bin2bcd(tm->tm_mon + 1);
+
+ buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;
+ if (tm->tm_year >= 100)
+ buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;
+ buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);
+
+ return spi_write(spi, buf, 8);
+}
+
+static int m41t94_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct spi_device *spi = to_spi_device(dev);
+ u8 buf[2];
+ int ret, hour;
+
+ /* clear halt update bit */
+ ret = spi_w8r8(spi, M41T94_REG_HT);
+ if (ret < 0)
+ return ret;
+ if (ret & M41T94_BIT_HALT) {
+ buf[0] = 0x80 | M41T94_REG_HT;
+ buf[1] = ret & ~M41T94_BIT_HALT;
+ spi_write(spi, buf, 2);
+ }
+
+ /* clear stop bit */
+ ret = spi_w8r8(spi, M41T94_REG_SECONDS);
+ if (ret < 0)
+ return ret;
+ if (ret & M41T94_BIT_STOP) {
+ buf[0] = 0x80 | M41T94_REG_SECONDS;
+ buf[1] = ret & ~M41T94_BIT_STOP;
+ spi_write(spi, buf, 2);
+ }
+
+ tm->tm_sec = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS));
+ tm->tm_min = bcd2bin(spi_w8r8(spi, M41T94_REG_MINUTES));
+ hour = spi_w8r8(spi, M41T94_REG_HOURS);
+ tm->tm_hour = bcd2bin(hour & 0x3f);
+ tm->tm_wday = bcd2bin(spi_w8r8(spi, M41T94_REG_WDAY)) - 1;
+ tm->tm_mday = bcd2bin(spi_w8r8(spi, M41T94_REG_DAY));
+ tm->tm_mon = bcd2bin(spi_w8r8(spi, M41T94_REG_MONTH)) - 1;
+ tm->tm_year = bcd2bin(spi_w8r8(spi, M41T94_REG_YEAR));
+ if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB))
+ tm->tm_year += 100;
+
+ dev_dbg(dev, "%s secs=%d, mins=%d, "
+ "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
+ "read", tm->tm_sec, tm->tm_min,
+ tm->tm_hour, tm->tm_mday,
+ tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+ return 0;
+}
+
+static const struct rtc_class_ops m41t94_rtc_ops = {
+ .read_time = m41t94_read_time,
+ .set_time = m41t94_set_time,
+};
+
+static struct spi_driver m41t94_driver;
+
+static int m41t94_probe(struct spi_device *spi)
+{
+ struct rtc_device *rtc;
+ int res;
+
+ spi->bits_per_word = 8;
+ spi_setup(spi);
+
+ res = spi_w8r8(spi, M41T94_REG_SECONDS);
+ if (res < 0) {
+ dev_err(&spi->dev, "not found.\n");
+ return res;
+ }
+
+ rtc = devm_rtc_device_register(&spi->dev, m41t94_driver.driver.name,
+ &m41t94_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ spi_set_drvdata(spi, rtc);
+
+ return 0;
+}
+
+static struct spi_driver m41t94_driver = {
+ .driver = {
+ .name = "rtc-m41t94",
+ },
+ .probe = m41t94_probe,
+};
+
+module_spi_driver(m41t94_driver);
+
+MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>");
+MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:rtc-m41t94");