mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-15 08:44:14 +08:00
fdcfd85433
rtc_register_device() is a managed interface but it doesn't use devres by itself - instead it marks an rtc_device as "registered" and the devres callback for devm_rtc_allocate_device() takes care of resource release. This doesn't correspond with the design behind devres where managed structures should not be aware of being managed. The correct solution here is to register a separate devres callback for unregistering the device. While at it: rename rtc_register_device() to devm_rtc_register_device() and add it to the list of managed interfaces in devres.rst. This way we can avoid any potential confusion of driver developers who may expect there to exist a corresponding unregister function. Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201109163409.24301-8-brgl@bgdev.pl
152 lines
3.5 KiB
C
152 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
|
|
/*
|
|
* rtc-dm355evm.c - access battery-backed counter in MSP430 firmware
|
|
*
|
|
* Copyright (c) 2008 by David Brownell
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
#include <linux/rtc.h>
|
|
#include <linux/platform_device.h>
|
|
|
|
#include <linux/mfd/dm355evm_msp.h>
|
|
#include <linux/module.h>
|
|
|
|
|
|
/*
|
|
* The MSP430 firmware on the DM355 EVM uses a watch crystal to feed
|
|
* a 1 Hz counter. When a backup battery is supplied, that makes a
|
|
* reasonable RTC for applications where alarms and non-NTP drift
|
|
* compensation aren't important.
|
|
*
|
|
* The only real glitch is the inability to read or write all four
|
|
* counter bytes atomically: the count may increment in the middle
|
|
* of an operation, causing trouble when the LSB rolls over.
|
|
*
|
|
* This driver was tested with firmware revision A4.
|
|
*/
|
|
union evm_time {
|
|
u8 bytes[4];
|
|
u32 value;
|
|
};
|
|
|
|
static int dm355evm_rtc_read_time(struct device *dev, struct rtc_time *tm)
|
|
{
|
|
union evm_time time;
|
|
int status;
|
|
int tries = 0;
|
|
|
|
do {
|
|
/*
|
|
* Read LSB(0) to MSB(3) bytes. Defend against the counter
|
|
* rolling over by re-reading until the value is stable,
|
|
* and assuming the four reads take at most a few seconds.
|
|
*/
|
|
status = dm355evm_msp_read(DM355EVM_MSP_RTC_0);
|
|
if (status < 0)
|
|
return status;
|
|
if (tries && time.bytes[0] == status)
|
|
break;
|
|
time.bytes[0] = status;
|
|
|
|
status = dm355evm_msp_read(DM355EVM_MSP_RTC_1);
|
|
if (status < 0)
|
|
return status;
|
|
if (tries && time.bytes[1] == status)
|
|
break;
|
|
time.bytes[1] = status;
|
|
|
|
status = dm355evm_msp_read(DM355EVM_MSP_RTC_2);
|
|
if (status < 0)
|
|
return status;
|
|
if (tries && time.bytes[2] == status)
|
|
break;
|
|
time.bytes[2] = status;
|
|
|
|
status = dm355evm_msp_read(DM355EVM_MSP_RTC_3);
|
|
if (status < 0)
|
|
return status;
|
|
if (tries && time.bytes[3] == status)
|
|
break;
|
|
time.bytes[3] = status;
|
|
|
|
} while (++tries < 5);
|
|
|
|
dev_dbg(dev, "read timestamp %08x\n", time.value);
|
|
|
|
rtc_time64_to_tm(le32_to_cpu(time.value), tm);
|
|
return 0;
|
|
}
|
|
|
|
static int dm355evm_rtc_set_time(struct device *dev, struct rtc_time *tm)
|
|
{
|
|
union evm_time time;
|
|
unsigned long value;
|
|
int status;
|
|
|
|
value = rtc_tm_to_time64(tm);
|
|
time.value = cpu_to_le32(value);
|
|
|
|
dev_dbg(dev, "write timestamp %08x\n", time.value);
|
|
|
|
/*
|
|
* REVISIT handle non-atomic writes ... maybe just retry until
|
|
* byte[1] sticks (no rollover)?
|
|
*/
|
|
status = dm355evm_msp_write(time.bytes[0], DM355EVM_MSP_RTC_0);
|
|
if (status < 0)
|
|
return status;
|
|
|
|
status = dm355evm_msp_write(time.bytes[1], DM355EVM_MSP_RTC_1);
|
|
if (status < 0)
|
|
return status;
|
|
|
|
status = dm355evm_msp_write(time.bytes[2], DM355EVM_MSP_RTC_2);
|
|
if (status < 0)
|
|
return status;
|
|
|
|
status = dm355evm_msp_write(time.bytes[3], DM355EVM_MSP_RTC_3);
|
|
if (status < 0)
|
|
return status;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct rtc_class_ops dm355evm_rtc_ops = {
|
|
.read_time = dm355evm_rtc_read_time,
|
|
.set_time = dm355evm_rtc_set_time,
|
|
};
|
|
|
|
/*----------------------------------------------------------------------*/
|
|
|
|
static int dm355evm_rtc_probe(struct platform_device *pdev)
|
|
{
|
|
struct rtc_device *rtc;
|
|
|
|
rtc = devm_rtc_allocate_device(&pdev->dev);
|
|
if (IS_ERR(rtc))
|
|
return PTR_ERR(rtc);
|
|
|
|
platform_set_drvdata(pdev, rtc);
|
|
|
|
rtc->ops = &dm355evm_rtc_ops;
|
|
rtc->range_max = U32_MAX;
|
|
|
|
return devm_rtc_register_device(rtc);
|
|
}
|
|
|
|
/*
|
|
* I2C is used to talk to the MSP430, but this platform device is
|
|
* exposed by an MFD driver that manages I2C communications.
|
|
*/
|
|
static struct platform_driver rtc_dm355evm_driver = {
|
|
.probe = dm355evm_rtc_probe,
|
|
.driver = {
|
|
.name = "rtc-dm355evm",
|
|
},
|
|
};
|
|
|
|
module_platform_driver(rtc_dm355evm_driver);
|
|
|
|
MODULE_LICENSE("GPL");
|