summaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-dm355evm.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/rtc/rtc-dm355evm.c')
-rw-r--r--drivers/rtc/rtc-dm355evm.c151
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");