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linux_kernel/drivers/rtc/rtc-hym8563.c
Paul Kocialkowski e2ed7507ae rtc: hym8563: Read the valid flag directly instead of caching it 
The RTC has a valid bit in the seconds register that indicates whether
power was lost since the pevious time set. This bit is currently read
once at probe time, cached and updated with set_time.

Howeever, caching the bit may prevent detecting power loss at runtime
(which can happen if the RTC's supply is distinct from the the platform's).

Writing the seconds register when setting time will clear the bit,
so there should be no downside in reading the bit directly instead of
caching it.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Link: https://lore.kernel.org/r/20191212153111.966923-2-paul.kocialkowski@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2019-12-23 11:18:06 +01:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Haoyu HYM8563 RTC driver
*
* Copyright (C) 2013 MundoReader S.L.
* Author: Heiko Stuebner <heiko@sntech.de>
*
* based on rtc-HYM8563
* Copyright (C) 2010 ROCKCHIP, Inc.
*/
#include <linux/module.h>
#include <linux/clk-provider.h>
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#define HYM8563_CTL1 0x00
#define HYM8563_CTL1_TEST BIT(7)
#define HYM8563_CTL1_STOP BIT(5)
#define HYM8563_CTL1_TESTC BIT(3)
#define HYM8563_CTL2 0x01
#define HYM8563_CTL2_TI_TP BIT(4)
#define HYM8563_CTL2_AF BIT(3)
#define HYM8563_CTL2_TF BIT(2)
#define HYM8563_CTL2_AIE BIT(1)
#define HYM8563_CTL2_TIE BIT(0)
#define HYM8563_SEC 0x02
#define HYM8563_SEC_VL BIT(7)
#define HYM8563_SEC_MASK 0x7f
#define HYM8563_MIN 0x03
#define HYM8563_MIN_MASK 0x7f
#define HYM8563_HOUR 0x04
#define HYM8563_HOUR_MASK 0x3f
#define HYM8563_DAY 0x05
#define HYM8563_DAY_MASK 0x3f
#define HYM8563_WEEKDAY 0x06
#define HYM8563_WEEKDAY_MASK 0x07
#define HYM8563_MONTH 0x07
#define HYM8563_MONTH_CENTURY BIT(7)
#define HYM8563_MONTH_MASK 0x1f
#define HYM8563_YEAR 0x08
#define HYM8563_ALM_MIN 0x09
#define HYM8563_ALM_HOUR 0x0a
#define HYM8563_ALM_DAY 0x0b
#define HYM8563_ALM_WEEK 0x0c
/* Each alarm check can be disabled by setting this bit in the register */
#define HYM8563_ALM_BIT_DISABLE BIT(7)
#define HYM8563_CLKOUT 0x0d
#define HYM8563_CLKOUT_ENABLE BIT(7)
#define HYM8563_CLKOUT_32768 0
#define HYM8563_CLKOUT_1024 1
#define HYM8563_CLKOUT_32 2
#define HYM8563_CLKOUT_1 3
#define HYM8563_CLKOUT_MASK 3
#define HYM8563_TMR_CTL 0x0e
#define HYM8563_TMR_CTL_ENABLE BIT(7)
#define HYM8563_TMR_CTL_4096 0
#define HYM8563_TMR_CTL_64 1
#define HYM8563_TMR_CTL_1 2
#define HYM8563_TMR_CTL_1_60 3
#define HYM8563_TMR_CTL_MASK 3
#define HYM8563_TMR_CNT 0x0f
struct hym8563 {
struct i2c_client *client;
struct rtc_device *rtc;
#ifdef CONFIG_COMMON_CLK
struct clk_hw clkout_hw;
#endif
};
/*
* RTC handling
*/
static int hym8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
u8 buf[7];
int ret;
ret = i2c_smbus_read_i2c_block_data(client, HYM8563_SEC, 7, buf);
if (ret < 0)
return ret;
if (buf[0] & HYM8563_SEC_VL) {
dev_warn(&client->dev,
"no valid clock/calendar values available\n");
return -EINVAL;
}
tm->tm_sec = bcd2bin(buf[0] & HYM8563_SEC_MASK);
tm->tm_min = bcd2bin(buf[1] & HYM8563_MIN_MASK);
tm->tm_hour = bcd2bin(buf[2] & HYM8563_HOUR_MASK);
tm->tm_mday = bcd2bin(buf[3] & HYM8563_DAY_MASK);
tm->tm_wday = bcd2bin(buf[4] & HYM8563_WEEKDAY_MASK); /* 0 = Sun */
tm->tm_mon = bcd2bin(buf[5] & HYM8563_MONTH_MASK) - 1; /* 0 = Jan */
tm->tm_year = bcd2bin(buf[6]) + 100;
return 0;
}
static int hym8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
u8 buf[7];
int ret;
/* Years >= 2100 are to far in the future, 19XX is to early */
if (tm->tm_year < 100 || tm->tm_year >= 200)
return -EINVAL;
buf[0] = bin2bcd(tm->tm_sec);
buf[1] = bin2bcd(tm->tm_min);
buf[2] = bin2bcd(tm->tm_hour);
buf[3] = bin2bcd(tm->tm_mday);
buf[4] = bin2bcd(tm->tm_wday);
buf[5] = bin2bcd(tm->tm_mon + 1);
/*
* While the HYM8563 has a century flag in the month register,
* it does not seem to carry it over a subsequent write/read.
* So we'll limit ourself to 100 years, starting at 2000 for now.
*/
buf[6] = bin2bcd(tm->tm_year - 100);
/*
* CTL1 only contains TEST-mode bits apart from stop,
* so no need to read the value first
*/
ret = i2c_smbus_write_byte_data(client, HYM8563_CTL1,
HYM8563_CTL1_STOP);
if (ret < 0)
return ret;
ret = i2c_smbus_write_i2c_block_data(client, HYM8563_SEC, 7, buf);
if (ret < 0)
return ret;
ret = i2c_smbus_write_byte_data(client, HYM8563_CTL1, 0);
if (ret < 0)
return ret;
return 0;
}
static int hym8563_rtc_alarm_irq_enable(struct device *dev,
unsigned int enabled)
{
struct i2c_client *client = to_i2c_client(dev);
int data;
data = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
if (data < 0)
return data;
if (enabled)
data |= HYM8563_CTL2_AIE;
else
data &= ~HYM8563_CTL2_AIE;
return i2c_smbus_write_byte_data(client, HYM8563_CTL2, data);
};
static int hym8563_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
struct i2c_client *client = to_i2c_client(dev);
struct rtc_time *alm_tm = &alm->time;
u8 buf[4];
int ret;
ret = i2c_smbus_read_i2c_block_data(client, HYM8563_ALM_MIN, 4, buf);
if (ret < 0)
return ret;
/* The alarm only has a minute accuracy */
alm_tm->tm_sec = 0;
alm_tm->tm_min = (buf[0] & HYM8563_ALM_BIT_DISABLE) ?
-1 :
bcd2bin(buf[0] & HYM8563_MIN_MASK);
alm_tm->tm_hour = (buf[1] & HYM8563_ALM_BIT_DISABLE) ?
-1 :
bcd2bin(buf[1] & HYM8563_HOUR_MASK);
alm_tm->tm_mday = (buf[2] & HYM8563_ALM_BIT_DISABLE) ?
-1 :
bcd2bin(buf[2] & HYM8563_DAY_MASK);
alm_tm->tm_wday = (buf[3] & HYM8563_ALM_BIT_DISABLE) ?
-1 :
bcd2bin(buf[3] & HYM8563_WEEKDAY_MASK);
ret = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
if (ret < 0)
return ret;
if (ret & HYM8563_CTL2_AIE)
alm->enabled = 1;
return 0;
}
static int hym8563_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
struct i2c_client *client = to_i2c_client(dev);
struct rtc_time *alm_tm = &alm->time;
u8 buf[4];
int ret;
/*
* The alarm has no seconds so deal with it
*/
if (alm_tm->tm_sec) {
alm_tm->tm_sec = 0;
alm_tm->tm_min++;
if (alm_tm->tm_min >= 60) {
alm_tm->tm_min = 0;
alm_tm->tm_hour++;
if (alm_tm->tm_hour >= 24) {
alm_tm->tm_hour = 0;
alm_tm->tm_mday++;
if (alm_tm->tm_mday > 31)
alm_tm->tm_mday = 0;
}
}
}
ret = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
if (ret < 0)
return ret;
ret &= ~HYM8563_CTL2_AIE;
ret = i2c_smbus_write_byte_data(client, HYM8563_CTL2, ret);
if (ret < 0)
return ret;
buf[0] = (alm_tm->tm_min < 60 && alm_tm->tm_min >= 0) ?
bin2bcd(alm_tm->tm_min) : HYM8563_ALM_BIT_DISABLE;
buf[1] = (alm_tm->tm_hour < 24 && alm_tm->tm_hour >= 0) ?
bin2bcd(alm_tm->tm_hour) : HYM8563_ALM_BIT_DISABLE;
buf[2] = (alm_tm->tm_mday <= 31 && alm_tm->tm_mday >= 1) ?
bin2bcd(alm_tm->tm_mday) : HYM8563_ALM_BIT_DISABLE;
buf[3] = (alm_tm->tm_wday < 7 && alm_tm->tm_wday >= 0) ?
bin2bcd(alm_tm->tm_wday) : HYM8563_ALM_BIT_DISABLE;
ret = i2c_smbus_write_i2c_block_data(client, HYM8563_ALM_MIN, 4, buf);
if (ret < 0)
return ret;
return hym8563_rtc_alarm_irq_enable(dev, alm->enabled);
}
static const struct rtc_class_ops hym8563_rtc_ops = {
.read_time = hym8563_rtc_read_time,
.set_time = hym8563_rtc_set_time,
.alarm_irq_enable = hym8563_rtc_alarm_irq_enable,
.read_alarm = hym8563_rtc_read_alarm,
.set_alarm = hym8563_rtc_set_alarm,
};
/*
* Handling of the clkout
*/
#ifdef CONFIG_COMMON_CLK
#define clkout_hw_to_hym8563(_hw) container_of(_hw, struct hym8563, clkout_hw)
static int clkout_rates[] = {
32768,
1024,
32,
1,
};
static unsigned long hym8563_clkout_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct hym8563 *hym8563 = clkout_hw_to_hym8563(hw);
struct i2c_client *client = hym8563->client;
int ret = i2c_smbus_read_byte_data(client, HYM8563_CLKOUT);
if (ret < 0)
return 0;
ret &= HYM8563_CLKOUT_MASK;
return clkout_rates[ret];
}
static long hym8563_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate)
{
int i;
for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
if (clkout_rates[i] <= rate)
return clkout_rates[i];
return 0;
}
static int hym8563_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct hym8563 *hym8563 = clkout_hw_to_hym8563(hw);
struct i2c_client *client = hym8563->client;
int ret = i2c_smbus_read_byte_data(client, HYM8563_CLKOUT);
int i;
if (ret < 0)
return ret;
for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
if (clkout_rates[i] == rate) {
ret &= ~HYM8563_CLKOUT_MASK;
ret |= i;
return i2c_smbus_write_byte_data(client,
HYM8563_CLKOUT, ret);
}
return -EINVAL;
}
static int hym8563_clkout_control(struct clk_hw *hw, bool enable)
{
struct hym8563 *hym8563 = clkout_hw_to_hym8563(hw);
struct i2c_client *client = hym8563->client;
int ret = i2c_smbus_read_byte_data(client, HYM8563_CLKOUT);
if (ret < 0)
return ret;
if (enable)
ret |= HYM8563_CLKOUT_ENABLE;
else
ret &= ~HYM8563_CLKOUT_ENABLE;
return i2c_smbus_write_byte_data(client, HYM8563_CLKOUT, ret);
}
static int hym8563_clkout_prepare(struct clk_hw *hw)
{
return hym8563_clkout_control(hw, 1);
}
static void hym8563_clkout_unprepare(struct clk_hw *hw)
{
hym8563_clkout_control(hw, 0);
}
static int hym8563_clkout_is_prepared(struct clk_hw *hw)
{
struct hym8563 *hym8563 = clkout_hw_to_hym8563(hw);
struct i2c_client *client = hym8563->client;
int ret = i2c_smbus_read_byte_data(client, HYM8563_CLKOUT);
if (ret < 0)
return ret;
return !!(ret & HYM8563_CLKOUT_ENABLE);
}
static const struct clk_ops hym8563_clkout_ops = {
.prepare = hym8563_clkout_prepare,
.unprepare = hym8563_clkout_unprepare,
.is_prepared = hym8563_clkout_is_prepared,
.recalc_rate = hym8563_clkout_recalc_rate,
.round_rate = hym8563_clkout_round_rate,
.set_rate = hym8563_clkout_set_rate,
};
static struct clk *hym8563_clkout_register_clk(struct hym8563 *hym8563)
{
struct i2c_client *client = hym8563->client;
struct device_node *node = client->dev.of_node;
struct clk *clk;
struct clk_init_data init;
int ret;
ret = i2c_smbus_write_byte_data(client, HYM8563_CLKOUT,
0);
if (ret < 0)
return ERR_PTR(ret);
init.name = "hym8563-clkout";
init.ops = &hym8563_clkout_ops;
init.flags = 0;
init.parent_names = NULL;
init.num_parents = 0;
hym8563->clkout_hw.init = &init;
/* optional override of the clockname */
of_property_read_string(node, "clock-output-names", &init.name);
/* register the clock */
clk = clk_register(&client->dev, &hym8563->clkout_hw);
if (!IS_ERR(clk))
of_clk_add_provider(node, of_clk_src_simple_get, clk);
return clk;
}
#endif
/*
* The alarm interrupt is implemented as a level-low interrupt in the
* hym8563, while the timer interrupt uses a falling edge.
* We don't use the timer at all, so the interrupt is requested to
* use the level-low trigger.
*/
static irqreturn_t hym8563_irq(int irq, void *dev_id)
{
struct hym8563 *hym8563 = (struct hym8563 *)dev_id;
struct i2c_client *client = hym8563->client;
struct mutex *lock = &hym8563->rtc->ops_lock;
int data, ret;
mutex_lock(lock);
/* Clear the alarm flag */
data = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
if (data < 0) {
dev_err(&client->dev, "%s: error reading i2c data %d\n",
__func__, data);
goto out;
}
data &= ~HYM8563_CTL2_AF;
ret = i2c_smbus_write_byte_data(client, HYM8563_CTL2, data);
if (ret < 0) {
dev_err(&client->dev, "%s: error writing i2c data %d\n",
__func__, ret);
}
out:
mutex_unlock(lock);
return IRQ_HANDLED;
}
static int hym8563_init_device(struct i2c_client *client)
{
int ret;
/* Clear stop flag if present */
ret = i2c_smbus_write_byte_data(client, HYM8563_CTL1, 0);
if (ret < 0)
return ret;
ret = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
if (ret < 0)
return ret;
/* Disable alarm and timer interrupts */
ret &= ~HYM8563_CTL2_AIE;
ret &= ~HYM8563_CTL2_TIE;
/* Clear any pending alarm and timer flags */
if (ret & HYM8563_CTL2_AF)
ret &= ~HYM8563_CTL2_AF;
if (ret & HYM8563_CTL2_TF)
ret &= ~HYM8563_CTL2_TF;
ret &= ~HYM8563_CTL2_TI_TP;
return i2c_smbus_write_byte_data(client, HYM8563_CTL2, ret);
}
#ifdef CONFIG_PM_SLEEP
static int hym8563_suspend(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
int ret;
if (device_may_wakeup(dev)) {
ret = enable_irq_wake(client->irq);
if (ret) {
dev_err(dev, "enable_irq_wake failed, %d\n", ret);
return ret;
}
}
return 0;
}
static int hym8563_resume(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
if (device_may_wakeup(dev))
disable_irq_wake(client->irq);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(hym8563_pm_ops, hym8563_suspend, hym8563_resume);
static int hym8563_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct hym8563 *hym8563;
int ret;
hym8563 = devm_kzalloc(&client->dev, sizeof(*hym8563), GFP_KERNEL);
if (!hym8563)
return -ENOMEM;
hym8563->client = client;
i2c_set_clientdata(client, hym8563);
device_set_wakeup_capable(&client->dev, true);
ret = hym8563_init_device(client);
if (ret) {
dev_err(&client->dev, "could not init device, %d\n", ret);
return ret;
}
if (client->irq > 0) {
ret = devm_request_threaded_irq(&client->dev, client->irq,
NULL, hym8563_irq,
IRQF_TRIGGER_LOW | IRQF_ONESHOT,
client->name, hym8563);
if (ret < 0) {
dev_err(&client->dev, "irq %d request failed, %d\n",
client->irq, ret);
return ret;
}
}
/* check state of calendar information */
ret = i2c_smbus_read_byte_data(client, HYM8563_SEC);
if (ret < 0)
return ret;
dev_dbg(&client->dev, "rtc information is %s\n",
(ret & HYM8563_SEC_VL) ? "invalid" : "valid");
hym8563->rtc = devm_rtc_device_register(&client->dev, client->name,
&hym8563_rtc_ops, THIS_MODULE);
if (IS_ERR(hym8563->rtc))
return PTR_ERR(hym8563->rtc);
/* the hym8563 alarm only supports a minute accuracy */
hym8563->rtc->uie_unsupported = 1;
#ifdef CONFIG_COMMON_CLK
hym8563_clkout_register_clk(hym8563);
#endif
return 0;
}
static const struct i2c_device_id hym8563_id[] = {
{ "hym8563", 0 },
{},
};
MODULE_DEVICE_TABLE(i2c, hym8563_id);
static const struct of_device_id hym8563_dt_idtable[] = {
{ .compatible = "haoyu,hym8563" },
{},
};
MODULE_DEVICE_TABLE(of, hym8563_dt_idtable);
static struct i2c_driver hym8563_driver = {
.driver = {
.name = "rtc-hym8563",
.pm = &hym8563_pm_ops,
.of_match_table = hym8563_dt_idtable,
},
.probe = hym8563_probe,
.id_table = hym8563_id,
};
module_i2c_driver(hym8563_driver);
MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
MODULE_DESCRIPTION("HYM8563 RTC driver");
MODULE_LICENSE("GPL");
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