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linux/drivers/rtc/rtc-msm6242.c
Kars de Jong 32c4d9e8a4 rtc: msm6242: Remove unneeded msm6242_set()/msm6242_clear() functions 
The msm6242_set()/msm6242_clear() functions are used when writing to Control
Register D to set or clear the HOLD bit when reading the current time from
the RTC.

Doing this with a read-modify-write cycle will potentially clear an
interrupt condition which occurs between the read and the write.

The datasheet states the following about this:

  When writing the HOLD or 30 second adjust bits of register D, it is
  necessary to write the IRQ FLAG bit to a "1".

Since the only other bits in the register are the 30 second adjust bit
(which is not used) and the BUSY bit (which is read-only), the
read-modify-write cycle can be replaced by a simple write with the IRQ FLAG
bit set to 1 and the other bits (except HOLD) set to 0.

Tested-by: Kars de Jong <jongk@linux-m68k.org>
Signed-off-by: Kars de Jong <jongk@linux-m68k.org>
Link: https://lore.kernel.org/r/20191116114620.9193-1-jongk@linux-m68k.org
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2019-11-18 15:23:54 +01:00

229 lines
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C
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Oki MSM6242 RTC Driver
*
* Copyright 2009 Geert Uytterhoeven
*
* Based on the A2000 TOD code in arch/m68k/amiga/config.c
* Copyright (C) 1993 Hamish Macdonald
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/slab.h>
enum {
MSM6242_SECOND1 = 0x0, /* 1-second digit register */
MSM6242_SECOND10 = 0x1, /* 10-second digit register */
MSM6242_MINUTE1 = 0x2, /* 1-minute digit register */
MSM6242_MINUTE10 = 0x3, /* 10-minute digit register */
MSM6242_HOUR1 = 0x4, /* 1-hour digit register */
MSM6242_HOUR10 = 0x5, /* PM/AM, 10-hour digit register */
MSM6242_DAY1 = 0x6, /* 1-day digit register */
MSM6242_DAY10 = 0x7, /* 10-day digit register */
MSM6242_MONTH1 = 0x8, /* 1-month digit register */
MSM6242_MONTH10 = 0x9, /* 10-month digit register */
MSM6242_YEAR1 = 0xa, /* 1-year digit register */
MSM6242_YEAR10 = 0xb, /* 10-year digit register */
MSM6242_WEEK = 0xc, /* Week register */
MSM6242_CD = 0xd, /* Control Register D */
MSM6242_CE = 0xe, /* Control Register E */
MSM6242_CF = 0xf, /* Control Register F */
};
#define MSM6242_HOUR10_AM (0 << 2)
#define MSM6242_HOUR10_PM (1 << 2)
#define MSM6242_HOUR10_HR_MASK (3 << 0)
#define MSM6242_WEEK_SUNDAY 0
#define MSM6242_WEEK_MONDAY 1
#define MSM6242_WEEK_TUESDAY 2
#define MSM6242_WEEK_WEDNESDAY 3
#define MSM6242_WEEK_THURSDAY 4
#define MSM6242_WEEK_FRIDAY 5
#define MSM6242_WEEK_SATURDAY 6
#define MSM6242_CD_30_S_ADJ (1 << 3) /* 30-second adjustment */
#define MSM6242_CD_IRQ_FLAG (1 << 2)
#define MSM6242_CD_BUSY (1 << 1)
#define MSM6242_CD_HOLD (1 << 0)
#define MSM6242_CE_T_MASK (3 << 2)
#define MSM6242_CE_T_64HZ (0 << 2) /* period 1/64 second */
#define MSM6242_CE_T_1HZ (1 << 2) /* period 1 second */
#define MSM6242_CE_T_1MINUTE (2 << 2) /* period 1 minute */
#define MSM6242_CE_T_1HOUR (3 << 2) /* period 1 hour */
#define MSM6242_CE_ITRPT_STND (1 << 1)
#define MSM6242_CE_MASK (1 << 0) /* STD.P output control */
#define MSM6242_CF_TEST (1 << 3)
#define MSM6242_CF_12H (0 << 2)
#define MSM6242_CF_24H (1 << 2)
#define MSM6242_CF_STOP (1 << 1)
#define MSM6242_CF_REST (1 << 0) /* reset */
struct msm6242_priv {
u32 __iomem *regs;
struct rtc_device *rtc;
};
static inline unsigned int msm6242_read(struct msm6242_priv *priv,
unsigned int reg)
{
return __raw_readl(&priv->regs[reg]) & 0xf;
}
static inline void msm6242_write(struct msm6242_priv *priv, unsigned int val,
unsigned int reg)
{
__raw_writel(val, &priv->regs[reg]);
}
static void msm6242_lock(struct msm6242_priv *priv)
{
int cnt = 5;
msm6242_write(priv, MSM6242_CD_HOLD|MSM6242_CD_IRQ_FLAG, MSM6242_CD);
while ((msm6242_read(priv, MSM6242_CD) & MSM6242_CD_BUSY) && cnt) {
msm6242_write(priv, MSM6242_CD_IRQ_FLAG, MSM6242_CD);
udelay(70);
msm6242_write(priv, MSM6242_CD_HOLD|MSM6242_CD_IRQ_FLAG, MSM6242_CD);
cnt--;
}
if (!cnt)
pr_warn("timed out waiting for RTC (0x%x)\n",
msm6242_read(priv, MSM6242_CD));
}
static void msm6242_unlock(struct msm6242_priv *priv)
{
msm6242_write(priv, MSM6242_CD_IRQ_FLAG, MSM6242_CD);
}
static int msm6242_read_time(struct device *dev, struct rtc_time *tm)
{
struct msm6242_priv *priv = dev_get_drvdata(dev);
msm6242_lock(priv);
tm->tm_sec = msm6242_read(priv, MSM6242_SECOND10) * 10 +
msm6242_read(priv, MSM6242_SECOND1);
tm->tm_min = msm6242_read(priv, MSM6242_MINUTE10) * 10 +
msm6242_read(priv, MSM6242_MINUTE1);
tm->tm_hour = (msm6242_read(priv, MSM6242_HOUR10) &
MSM6242_HOUR10_HR_MASK) * 10 +
msm6242_read(priv, MSM6242_HOUR1);
tm->tm_mday = msm6242_read(priv, MSM6242_DAY10) * 10 +
msm6242_read(priv, MSM6242_DAY1);
tm->tm_wday = msm6242_read(priv, MSM6242_WEEK);
tm->tm_mon = msm6242_read(priv, MSM6242_MONTH10) * 10 +
msm6242_read(priv, MSM6242_MONTH1) - 1;
tm->tm_year = msm6242_read(priv, MSM6242_YEAR10) * 10 +
msm6242_read(priv, MSM6242_YEAR1);
if (tm->tm_year <= 69)
tm->tm_year += 100;
if (!(msm6242_read(priv, MSM6242_CF) & MSM6242_CF_24H)) {
unsigned int pm = msm6242_read(priv, MSM6242_HOUR10) &
MSM6242_HOUR10_PM;
if (!pm && tm->tm_hour == 12)
tm->tm_hour = 0;
else if (pm && tm->tm_hour != 12)
tm->tm_hour += 12;
}
msm6242_unlock(priv);
return 0;
}
static int msm6242_set_time(struct device *dev, struct rtc_time *tm)
{
struct msm6242_priv *priv = dev_get_drvdata(dev);
msm6242_lock(priv);
msm6242_write(priv, tm->tm_sec / 10, MSM6242_SECOND10);
msm6242_write(priv, tm->tm_sec % 10, MSM6242_SECOND1);
msm6242_write(priv, tm->tm_min / 10, MSM6242_MINUTE10);
msm6242_write(priv, tm->tm_min % 10, MSM6242_MINUTE1);
if (msm6242_read(priv, MSM6242_CF) & MSM6242_CF_24H)
msm6242_write(priv, tm->tm_hour / 10, MSM6242_HOUR10);
else if (tm->tm_hour >= 12)
msm6242_write(priv, MSM6242_HOUR10_PM + (tm->tm_hour - 12) / 10,
MSM6242_HOUR10);
else
msm6242_write(priv, tm->tm_hour / 10, MSM6242_HOUR10);
msm6242_write(priv, tm->tm_hour % 10, MSM6242_HOUR1);
msm6242_write(priv, tm->tm_mday / 10, MSM6242_DAY10);
msm6242_write(priv, tm->tm_mday % 10, MSM6242_DAY1);
if (tm->tm_wday != -1)
msm6242_write(priv, tm->tm_wday, MSM6242_WEEK);
msm6242_write(priv, (tm->tm_mon + 1) / 10, MSM6242_MONTH10);
msm6242_write(priv, (tm->tm_mon + 1) % 10, MSM6242_MONTH1);
if (tm->tm_year >= 100)
tm->tm_year -= 100;
msm6242_write(priv, tm->tm_year / 10, MSM6242_YEAR10);
msm6242_write(priv, tm->tm_year % 10, MSM6242_YEAR1);
msm6242_unlock(priv);
return 0;
}
static const struct rtc_class_ops msm6242_rtc_ops = {
.read_time = msm6242_read_time,
.set_time = msm6242_set_time,
};
static int __init msm6242_rtc_probe(struct platform_device *pdev)
{
struct resource *res;
struct msm6242_priv *priv;
struct rtc_device *rtc;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->regs = devm_ioremap(&pdev->dev, res->start, resource_size(res));
if (!priv->regs)
return -ENOMEM;
platform_set_drvdata(pdev, priv);
rtc = devm_rtc_device_register(&pdev->dev, "rtc-msm6242",
&msm6242_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
priv->rtc = rtc;
return 0;
}
static struct platform_driver msm6242_rtc_driver = {
.driver = {
.name = "rtc-msm6242",
},
};
module_platform_driver_probe(msm6242_rtc_driver, msm6242_rtc_probe);
MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Oki MSM6242 RTC driver");
MODULE_ALIAS("platform:rtc-msm6242");
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