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linux/drivers/rtc/rtc-r7301.c
Linus Walleij 8c767e9c1e rtc: rtc7301: Support byte-addressed IO 
The old RTC7301 driver in OpenWrt used byte access, but the
current mainline Linux driver uses 32bit word access.

Make this configurable using device properties using the
standard property "reg-io-width" in e.g. device tree.

This is needed for the USRobotics USR8200 which has the
chip connected using byte accesses.

Debugging and testing by Howard Harte.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Akinobu Mita <akinobu.mita@gmail.com>
Link: https://lore.kernel.org/r/20231010-rtc-7301-regwidth-v3-2-ade586b62794@linaro.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2023-10-15 22:37:25 +02:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* EPSON TOYOCOM RTC-7301SF/DG Driver
*
* Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
*
* Based on rtc-rp5c01.c
*
* Datasheet: http://www5.epsondevice.com/en/products/parallel/rtc7301sf.html
*/
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/delay.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#define DRV_NAME "rtc-r7301"
#define RTC7301_1_SEC 0x0 /* Bank 0 and Band 1 */
#define RTC7301_10_SEC 0x1 /* Bank 0 and Band 1 */
#define RTC7301_AE BIT(3)
#define RTC7301_1_MIN 0x2 /* Bank 0 and Band 1 */
#define RTC7301_10_MIN 0x3 /* Bank 0 and Band 1 */
#define RTC7301_1_HOUR 0x4 /* Bank 0 and Band 1 */
#define RTC7301_10_HOUR 0x5 /* Bank 0 and Band 1 */
#define RTC7301_DAY_OF_WEEK 0x6 /* Bank 0 and Band 1 */
#define RTC7301_1_DAY 0x7 /* Bank 0 and Band 1 */
#define RTC7301_10_DAY 0x8 /* Bank 0 and Band 1 */
#define RTC7301_1_MONTH 0x9 /* Bank 0 */
#define RTC7301_10_MONTH 0xa /* Bank 0 */
#define RTC7301_1_YEAR 0xb /* Bank 0 */
#define RTC7301_10_YEAR 0xc /* Bank 0 */
#define RTC7301_100_YEAR 0xd /* Bank 0 */
#define RTC7301_1000_YEAR 0xe /* Bank 0 */
#define RTC7301_ALARM_CONTROL 0xe /* Bank 1 */
#define RTC7301_ALARM_CONTROL_AIE BIT(0)
#define RTC7301_ALARM_CONTROL_AF BIT(1)
#define RTC7301_TIMER_CONTROL 0xe /* Bank 2 */
#define RTC7301_TIMER_CONTROL_TIE BIT(0)
#define RTC7301_TIMER_CONTROL_TF BIT(1)
#define RTC7301_CONTROL 0xf /* All banks */
#define RTC7301_CONTROL_BUSY BIT(0)
#define RTC7301_CONTROL_STOP BIT(1)
#define RTC7301_CONTROL_BANK_SEL_0 BIT(2)
#define RTC7301_CONTROL_BANK_SEL_1 BIT(3)
struct rtc7301_priv {
struct regmap *regmap;
int irq;
spinlock_t lock;
u8 bank;
};
/*
* When the device is memory-mapped, some platforms pack the registers into
* 32-bit access using the lower 8 bits at each 4-byte stride, while others
* expose them as simply consecutive bytes.
*/
static const struct regmap_config rtc7301_regmap_32_config = {
.reg_bits = 32,
.val_bits = 8,
.reg_stride = 4,
};
static const struct regmap_config rtc7301_regmap_8_config = {
.reg_bits = 8,
.val_bits = 8,
.reg_stride = 1,
};
static u8 rtc7301_read(struct rtc7301_priv *priv, unsigned int reg)
{
int reg_stride = regmap_get_reg_stride(priv->regmap);
unsigned int val;
regmap_read(priv->regmap, reg_stride * reg, &val);
return val & 0xf;
}
static void rtc7301_write(struct rtc7301_priv *priv, u8 val, unsigned int reg)
{
int reg_stride = regmap_get_reg_stride(priv->regmap);
regmap_write(priv->regmap, reg_stride * reg, val);
}
static void rtc7301_update_bits(struct rtc7301_priv *priv, unsigned int reg,
u8 mask, u8 val)
{
int reg_stride = regmap_get_reg_stride(priv->regmap);
regmap_update_bits(priv->regmap, reg_stride * reg, mask, val);
}
static int rtc7301_wait_while_busy(struct rtc7301_priv *priv)
{
int retries = 100;
while (retries-- > 0) {
u8 val;
val = rtc7301_read(priv, RTC7301_CONTROL);
if (!(val & RTC7301_CONTROL_BUSY))
return 0;
udelay(300);
}
return -ETIMEDOUT;
}
static void rtc7301_stop(struct rtc7301_priv *priv)
{
rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP,
RTC7301_CONTROL_STOP);
}
static void rtc7301_start(struct rtc7301_priv *priv)
{
rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP, 0);
}
static void rtc7301_select_bank(struct rtc7301_priv *priv, u8 bank)
{
u8 val = 0;
if (bank == priv->bank)
return;
if (bank & BIT(0))
val |= RTC7301_CONTROL_BANK_SEL_0;
if (bank & BIT(1))
val |= RTC7301_CONTROL_BANK_SEL_1;
rtc7301_update_bits(priv, RTC7301_CONTROL,
RTC7301_CONTROL_BANK_SEL_0 |
RTC7301_CONTROL_BANK_SEL_1, val);
priv->bank = bank;
}
static void rtc7301_get_time(struct rtc7301_priv *priv, struct rtc_time *tm,
bool alarm)
{
int year;
tm->tm_sec = rtc7301_read(priv, RTC7301_1_SEC);
tm->tm_sec += (rtc7301_read(priv, RTC7301_10_SEC) & ~RTC7301_AE) * 10;
tm->tm_min = rtc7301_read(priv, RTC7301_1_MIN);
tm->tm_min += (rtc7301_read(priv, RTC7301_10_MIN) & ~RTC7301_AE) * 10;
tm->tm_hour = rtc7301_read(priv, RTC7301_1_HOUR);
tm->tm_hour += (rtc7301_read(priv, RTC7301_10_HOUR) & ~RTC7301_AE) * 10;
tm->tm_mday = rtc7301_read(priv, RTC7301_1_DAY);
tm->tm_mday += (rtc7301_read(priv, RTC7301_10_DAY) & ~RTC7301_AE) * 10;
if (alarm) {
tm->tm_wday = -1;
tm->tm_mon = -1;
tm->tm_year = -1;
tm->tm_yday = -1;
tm->tm_isdst = -1;
return;
}
tm->tm_wday = (rtc7301_read(priv, RTC7301_DAY_OF_WEEK) & ~RTC7301_AE);
tm->tm_mon = rtc7301_read(priv, RTC7301_10_MONTH) * 10 +
rtc7301_read(priv, RTC7301_1_MONTH) - 1;
year = rtc7301_read(priv, RTC7301_1000_YEAR) * 1000 +
rtc7301_read(priv, RTC7301_100_YEAR) * 100 +
rtc7301_read(priv, RTC7301_10_YEAR) * 10 +
rtc7301_read(priv, RTC7301_1_YEAR);
tm->tm_year = year - 1900;
}
static void rtc7301_write_time(struct rtc7301_priv *priv, struct rtc_time *tm,
bool alarm)
{
int year;
rtc7301_write(priv, tm->tm_sec % 10, RTC7301_1_SEC);
rtc7301_write(priv, tm->tm_sec / 10, RTC7301_10_SEC);
rtc7301_write(priv, tm->tm_min % 10, RTC7301_1_MIN);
rtc7301_write(priv, tm->tm_min / 10, RTC7301_10_MIN);
rtc7301_write(priv, tm->tm_hour % 10, RTC7301_1_HOUR);
rtc7301_write(priv, tm->tm_hour / 10, RTC7301_10_HOUR);
rtc7301_write(priv, tm->tm_mday % 10, RTC7301_1_DAY);
rtc7301_write(priv, tm->tm_mday / 10, RTC7301_10_DAY);
/* Don't care for alarm register */
rtc7301_write(priv, alarm ? RTC7301_AE : tm->tm_wday,
RTC7301_DAY_OF_WEEK);
if (alarm)
return;
rtc7301_write(priv, (tm->tm_mon + 1) % 10, RTC7301_1_MONTH);
rtc7301_write(priv, (tm->tm_mon + 1) / 10, RTC7301_10_MONTH);
year = tm->tm_year + 1900;
rtc7301_write(priv, year % 10, RTC7301_1_YEAR);
rtc7301_write(priv, (year / 10) % 10, RTC7301_10_YEAR);
rtc7301_write(priv, (year / 100) % 10, RTC7301_100_YEAR);
rtc7301_write(priv, year / 1000, RTC7301_1000_YEAR);
}
static void rtc7301_alarm_irq(struct rtc7301_priv *priv, unsigned int enabled)
{
rtc7301_update_bits(priv, RTC7301_ALARM_CONTROL,
RTC7301_ALARM_CONTROL_AF |
RTC7301_ALARM_CONTROL_AIE,
enabled ? RTC7301_ALARM_CONTROL_AIE : 0);
}
static int rtc7301_read_time(struct device *dev, struct rtc_time *tm)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
int err;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 0);
err = rtc7301_wait_while_busy(priv);
if (!err)
rtc7301_get_time(priv, tm, false);
spin_unlock_irqrestore(&priv->lock, flags);
return err;
}
static int rtc7301_set_time(struct device *dev, struct rtc_time *tm)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_stop(priv);
udelay(300);
rtc7301_select_bank(priv, 0);
rtc7301_write_time(priv, tm, false);
rtc7301_start(priv);
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
static int rtc7301_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
u8 alrm_ctrl;
if (priv->irq <= 0)
return -EINVAL;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 1);
rtc7301_get_time(priv, &alarm->time, true);
alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);
alarm->enabled = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AIE);
alarm->pending = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AF);
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
static int rtc7301_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
if (priv->irq <= 0)
return -EINVAL;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 1);
rtc7301_write_time(priv, &alarm->time, true);
rtc7301_alarm_irq(priv, alarm->enabled);
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
static int rtc7301_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
if (priv->irq <= 0)
return -EINVAL;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 1);
rtc7301_alarm_irq(priv, enabled);
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
static const struct rtc_class_ops rtc7301_rtc_ops = {
.read_time = rtc7301_read_time,
.set_time = rtc7301_set_time,
.read_alarm = rtc7301_read_alarm,
.set_alarm = rtc7301_set_alarm,
.alarm_irq_enable = rtc7301_alarm_irq_enable,
};
static irqreturn_t rtc7301_irq_handler(int irq, void *dev_id)
{
struct rtc_device *rtc = dev_id;
struct rtc7301_priv *priv = dev_get_drvdata(rtc->dev.parent);
irqreturn_t ret = IRQ_NONE;
u8 alrm_ctrl;
spin_lock(&priv->lock);
rtc7301_select_bank(priv, 1);
alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);
if (alrm_ctrl & RTC7301_ALARM_CONTROL_AF) {
ret = IRQ_HANDLED;
rtc7301_alarm_irq(priv, false);
rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
}
spin_unlock(&priv->lock);
return ret;
}
static void rtc7301_init(struct rtc7301_priv *priv)
{
unsigned long flags;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 2);
rtc7301_write(priv, 0, RTC7301_TIMER_CONTROL);
spin_unlock_irqrestore(&priv->lock, flags);
}
static int __init rtc7301_rtc_probe(struct platform_device *dev)
{
void __iomem *regs;
struct rtc7301_priv *priv;
struct rtc_device *rtc;
static const struct regmap_config *mapconf;
int ret;
u32 val;
priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
regs = devm_platform_ioremap_resource(dev, 0);
if (IS_ERR(regs))
return PTR_ERR(regs);
ret = device_property_read_u32(&dev->dev, "reg-io-width", &val);
if (ret)
/* Default to 32bit accesses */
val = 4;
switch (val) {
case 1:
mapconf = &rtc7301_regmap_8_config;
break;
case 4:
mapconf = &rtc7301_regmap_32_config;
break;
default:
dev_err(&dev->dev, "invalid reg-io-width %d\n", val);
return -EINVAL;
}
priv->regmap = devm_regmap_init_mmio(&dev->dev, regs,
mapconf);
if (IS_ERR(priv->regmap))
return PTR_ERR(priv->regmap);
priv->irq = platform_get_irq(dev, 0);
spin_lock_init(&priv->lock);
priv->bank = -1;
rtc7301_init(priv);
platform_set_drvdata(dev, priv);
rtc = devm_rtc_device_register(&dev->dev, DRV_NAME, &rtc7301_rtc_ops,
THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
if (priv->irq > 0) {
ret = devm_request_irq(&dev->dev, priv->irq,
rtc7301_irq_handler, IRQF_SHARED,
dev_name(&dev->dev), rtc);
if (ret) {
priv->irq = 0;
dev_err(&dev->dev, "unable to request IRQ\n");
} else {
device_set_wakeup_capable(&dev->dev, true);
}
}
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int rtc7301_suspend(struct device *dev)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
if (device_may_wakeup(dev))
enable_irq_wake(priv->irq);
return 0;
}
static int rtc7301_resume(struct device *dev)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
if (device_may_wakeup(dev))
disable_irq_wake(priv->irq);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(rtc7301_pm_ops, rtc7301_suspend, rtc7301_resume);
static const struct of_device_id rtc7301_dt_match[] = {
{ .compatible = "epson,rtc7301sf" },
{ .compatible = "epson,rtc7301dg" },
{}
};
MODULE_DEVICE_TABLE(of, rtc7301_dt_match);
static struct platform_driver rtc7301_rtc_driver = {
.driver = {
.name = DRV_NAME,
.of_match_table = rtc7301_dt_match,
.pm = &rtc7301_pm_ops,
},
};
module_platform_driver_probe(rtc7301_rtc_driver, rtc7301_rtc_probe);
MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("EPSON TOYOCOM RTC-7301SF/DG Driver");
MODULE_ALIAS("platform:rtc-r7301");
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