diff options
Diffstat (limited to 'drivers/rtc/rtc-dm355evm.c')
-rw-r--r-- | drivers/rtc/rtc-dm355evm.c | 151 |
1 files changed, 0 insertions, 151 deletions
diff --git a/drivers/rtc/rtc-dm355evm.c b/drivers/rtc/rtc-dm355evm.c deleted file mode 100644 index 94fb16ac3e0f..000000000000 --- a/drivers/rtc/rtc-dm355evm.c +++ /dev/null @@ -1,151 +0,0 @@ -// 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"); |