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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
| commit | 4352b8aee98005853aa63f57d6377282de17a33f (patch) | |
| tree | 27614d7a9ef05c32d089004e104364ce42324837 /drivers/rtc/rtc-max6900.c | |
| download | linux-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-max6900.c')
| -rw-r--r-- | drivers/rtc/rtc-max6900.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-max6900.c b/drivers/rtc/rtc-max6900.c new file mode 100644 index 000000000..8ef6d0fcd --- /dev/null +++ b/drivers/rtc/rtc-max6900.c @@ -0,0 +1,235 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * rtc class driver for the Maxim MAX6900 chip + * + * Copyright (c) 2007 MontaVista, Software, Inc. + * + * Author: Dale Farnsworth <dale@farnsworth.org> + * + * based on previously existing rtc class drivers + */ + +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/bcd.h> +#include <linux/rtc.h> +#include <linux/delay.h> + +/* + * register indices + */ +#define MAX6900_REG_SC 0 /* seconds 00-59 */ +#define MAX6900_REG_MN 1 /* minutes 00-59 */ +#define MAX6900_REG_HR 2 /* hours 00-23 */ +#define MAX6900_REG_DT 3 /* day of month 00-31 */ +#define MAX6900_REG_MO 4 /* month 01-12 */ +#define MAX6900_REG_DW 5 /* day of week 1-7 */ +#define MAX6900_REG_YR 6 /* year 00-99 */ +#define MAX6900_REG_CT 7 /* control */ + /* register 8 is undocumented */ +#define MAX6900_REG_CENTURY 9 /* century */ +#define MAX6900_REG_LEN 10 + +#define MAX6900_BURST_LEN 8 /* can burst r/w first 8 regs */ + +#define MAX6900_REG_CT_WP (1 << 7) /* Write Protect */ + +/* + * register read/write commands + */ +#define MAX6900_REG_CONTROL_WRITE 0x8e +#define MAX6900_REG_CENTURY_WRITE 0x92 +#define MAX6900_REG_CENTURY_READ 0x93 +#define MAX6900_REG_RESERVED_READ 0x96 +#define MAX6900_REG_BURST_WRITE 0xbe +#define MAX6900_REG_BURST_READ 0xbf + +#define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */ + +static struct i2c_driver max6900_driver; + +static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf) +{ + u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ }; + u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ }; + struct i2c_msg msgs[4] = { + { + .addr = client->addr, + .flags = 0, /* write */ + .len = sizeof(reg_burst_read), + .buf = reg_burst_read} + , + { + .addr = client->addr, + .flags = I2C_M_RD, + .len = MAX6900_BURST_LEN, + .buf = buf} + , + { + .addr = client->addr, + .flags = 0, /* write */ + .len = sizeof(reg_century_read), + .buf = reg_century_read} + , + { + .addr = client->addr, + .flags = I2C_M_RD, + .len = sizeof(buf[MAX6900_REG_CENTURY]), + .buf = &buf[MAX6900_REG_CENTURY] + } + }; + int rc; + + rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); + if (rc != ARRAY_SIZE(msgs)) { + dev_err(&client->dev, "%s: register read failed\n", __func__); + return -EIO; + } + return 0; +} + +static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf) +{ + u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE }; + struct i2c_msg century_msgs[1] = { + { + .addr = client->addr, + .flags = 0, /* write */ + .len = sizeof(i2c_century_buf), + .buf = i2c_century_buf} + }; + u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE }; + struct i2c_msg burst_msgs[1] = { + { + .addr = client->addr, + .flags = 0, /* write */ + .len = sizeof(i2c_burst_buf), + .buf = i2c_burst_buf} + }; + int rc; + + /* + * We have to make separate calls to i2c_transfer because of + * the need to delay after each write to the chip. Also, + * we write the century byte first, since we set the write-protect + * bit as part of the burst write. + */ + i2c_century_buf[1] = buf[MAX6900_REG_CENTURY]; + + rc = i2c_transfer(client->adapter, century_msgs, + ARRAY_SIZE(century_msgs)); + if (rc != ARRAY_SIZE(century_msgs)) + goto write_failed; + + msleep(MAX6900_IDLE_TIME_AFTER_WRITE); + + memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN); + + rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs)); + if (rc != ARRAY_SIZE(burst_msgs)) + goto write_failed; + msleep(MAX6900_IDLE_TIME_AFTER_WRITE); + + return 0; + + write_failed: + dev_err(&client->dev, "%s: register write failed\n", __func__); + return -EIO; +} + +static int max6900_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + int rc; + u8 regs[MAX6900_REG_LEN]; + + rc = max6900_i2c_read_regs(client, regs); + if (rc < 0) + return rc; + + tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]); + tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]); + tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f); + tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]); + tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1; + tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) + + bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900; + tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]); + + return 0; +} + +static int max6900_i2c_clear_write_protect(struct i2c_client *client) +{ + return i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0); +} + +static int max6900_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + u8 regs[MAX6900_REG_LEN]; + int rc; + + rc = max6900_i2c_clear_write_protect(client); + if (rc < 0) + return rc; + + regs[MAX6900_REG_SC] = bin2bcd(tm->tm_sec); + regs[MAX6900_REG_MN] = bin2bcd(tm->tm_min); + regs[MAX6900_REG_HR] = bin2bcd(tm->tm_hour); + regs[MAX6900_REG_DT] = bin2bcd(tm->tm_mday); + regs[MAX6900_REG_MO] = bin2bcd(tm->tm_mon + 1); + regs[MAX6900_REG_DW] = bin2bcd(tm->tm_wday); + regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100); + regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100); + /* set write protect */ + regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP; + + rc = max6900_i2c_write_regs(client, regs); + if (rc < 0) + return rc; + + return 0; +} + +static const struct rtc_class_ops max6900_rtc_ops = { + .read_time = max6900_rtc_read_time, + .set_time = max6900_rtc_set_time, +}; + +static int max6900_probe(struct i2c_client *client) +{ + struct rtc_device *rtc; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name, + &max6900_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + i2c_set_clientdata(client, rtc); + + return 0; +} + +static const struct i2c_device_id max6900_id[] = { + { .name = "max6900" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, max6900_id); + +static struct i2c_driver max6900_driver = { + .driver = { + .name = "rtc-max6900", + }, + .probe = max6900_probe, + .id_table = max6900_id, +}; + +module_i2c_driver(max6900_driver); + +MODULE_DESCRIPTION("Maxim MAX6900 RTC driver"); +MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>"); +MODULE_LICENSE("GPL"); |
