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linux/drivers/rtc/rtc-v3020.c
Colin Ian King fc3c335226 rtc: v3020: remove redundant initialization of variable retval 
The variable retval is being initialized with a value that is never read,
it is being updated later on. The assignment is redundant and can be
removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210609120050.185746-1-colin.king@canonical.com
2021-06-20 22:29:50 +02:00

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// SPDX-License-Identifier: GPL-2.0-only
/* drivers/rtc/rtc-v3020.c
*
* Copyright (C) 2006 8D Technologies inc.
* Copyright (C) 2004 Compulab Ltd.
*
* Driver for the V3020 RTC
*
* Changelog:
*
* 10-May-2006: Raphael Assenat <raph@8d.com>
* - Converted to platform driver
* - Use the generic rtc class
*
* ??-???-2004: Someone at Compulab
* - Initial driver creation.
*/
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/types.h>
#include <linux/bcd.h>
#include <linux/platform_data/rtc-v3020.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/io.h>
#undef DEBUG
struct v3020;
struct v3020_chip_ops {
int (*map_io)(struct v3020 *chip, struct platform_device *pdev,
struct v3020_platform_data *pdata);
void (*unmap_io)(struct v3020 *chip);
unsigned char (*read_bit)(struct v3020 *chip);
void (*write_bit)(struct v3020 *chip, unsigned char bit);
};
#define V3020_CS 0
#define V3020_WR 1
#define V3020_RD 2
#define V3020_IO 3
struct v3020 {
/* MMIO access */
void __iomem *ioaddress;
int leftshift;
/* GPIO access */
struct gpio *gpio;
const struct v3020_chip_ops *ops;
struct rtc_device *rtc;
};
static int v3020_mmio_map(struct v3020 *chip, struct platform_device *pdev,
struct v3020_platform_data *pdata)
{
if (pdev->num_resources != 1)
return -EBUSY;
if (pdev->resource[0].flags != IORESOURCE_MEM)
return -EBUSY;
chip->leftshift = pdata->leftshift;
chip->ioaddress = ioremap(pdev->resource[0].start, 1);
if (chip->ioaddress == NULL)
return -EBUSY;
return 0;
}
static void v3020_mmio_unmap(struct v3020 *chip)
{
iounmap(chip->ioaddress);
}
static void v3020_mmio_write_bit(struct v3020 *chip, unsigned char bit)
{
writel(bit << chip->leftshift, chip->ioaddress);
}
static unsigned char v3020_mmio_read_bit(struct v3020 *chip)
{
return !!(readl(chip->ioaddress) & (1 << chip->leftshift));
}
static const struct v3020_chip_ops v3020_mmio_ops = {
.map_io = v3020_mmio_map,
.unmap_io = v3020_mmio_unmap,
.read_bit = v3020_mmio_read_bit,
.write_bit = v3020_mmio_write_bit,
};
static struct gpio v3020_gpio[] = {
{ 0, GPIOF_OUT_INIT_HIGH, "RTC CS"},
{ 0, GPIOF_OUT_INIT_HIGH, "RTC WR"},
{ 0, GPIOF_OUT_INIT_HIGH, "RTC RD"},
{ 0, GPIOF_OUT_INIT_HIGH, "RTC IO"},
};
static int v3020_gpio_map(struct v3020 *chip, struct platform_device *pdev,
struct v3020_platform_data *pdata)
{
int err;
v3020_gpio[V3020_CS].gpio = pdata->gpio_cs;
v3020_gpio[V3020_WR].gpio = pdata->gpio_wr;
v3020_gpio[V3020_RD].gpio = pdata->gpio_rd;
v3020_gpio[V3020_IO].gpio = pdata->gpio_io;
err = gpio_request_array(v3020_gpio, ARRAY_SIZE(v3020_gpio));
if (!err)
chip->gpio = v3020_gpio;
return err;
}
static void v3020_gpio_unmap(struct v3020 *chip)
{
gpio_free_array(v3020_gpio, ARRAY_SIZE(v3020_gpio));
}
static void v3020_gpio_write_bit(struct v3020 *chip, unsigned char bit)
{
gpio_direction_output(chip->gpio[V3020_IO].gpio, bit);
gpio_set_value(chip->gpio[V3020_CS].gpio, 0);
gpio_set_value(chip->gpio[V3020_WR].gpio, 0);
udelay(1);
gpio_set_value(chip->gpio[V3020_WR].gpio, 1);
gpio_set_value(chip->gpio[V3020_CS].gpio, 1);
}
static unsigned char v3020_gpio_read_bit(struct v3020 *chip)
{
int bit;
gpio_direction_input(chip->gpio[V3020_IO].gpio);
gpio_set_value(chip->gpio[V3020_CS].gpio, 0);
gpio_set_value(chip->gpio[V3020_RD].gpio, 0);
udelay(1);
bit = !!gpio_get_value(chip->gpio[V3020_IO].gpio);
udelay(1);
gpio_set_value(chip->gpio[V3020_RD].gpio, 1);
gpio_set_value(chip->gpio[V3020_CS].gpio, 1);
return bit;
}
static const struct v3020_chip_ops v3020_gpio_ops = {
.map_io = v3020_gpio_map,
.unmap_io = v3020_gpio_unmap,
.read_bit = v3020_gpio_read_bit,
.write_bit = v3020_gpio_write_bit,
};
static void v3020_set_reg(struct v3020 *chip, unsigned char address,
unsigned char data)
{
int i;
unsigned char tmp;
tmp = address;
for (i = 0; i < 4; i++) {
chip->ops->write_bit(chip, (tmp & 1));
tmp >>= 1;
udelay(1);
}
/* Commands dont have data */
if (!V3020_IS_COMMAND(address)) {
for (i = 0; i < 8; i++) {
chip->ops->write_bit(chip, (data & 1));
data >>= 1;
udelay(1);
}
}
}
static unsigned char v3020_get_reg(struct v3020 *chip, unsigned char address)
{
unsigned int data = 0;
int i;
for (i = 0; i < 4; i++) {
chip->ops->write_bit(chip, (address & 1));
address >>= 1;
udelay(1);
}
for (i = 0; i < 8; i++) {
data >>= 1;
if (chip->ops->read_bit(chip))
data |= 0x80;
udelay(1);
}
return data;
}
static int v3020_read_time(struct device *dev, struct rtc_time *dt)
{
struct v3020 *chip = dev_get_drvdata(dev);
int tmp;
/* Copy the current time to ram... */
v3020_set_reg(chip, V3020_CMD_CLOCK2RAM, 0);
/* ...and then read constant values. */
tmp = v3020_get_reg(chip, V3020_SECONDS);
dt->tm_sec = bcd2bin(tmp);
tmp = v3020_get_reg(chip, V3020_MINUTES);
dt->tm_min = bcd2bin(tmp);
tmp = v3020_get_reg(chip, V3020_HOURS);
dt->tm_hour = bcd2bin(tmp);
tmp = v3020_get_reg(chip, V3020_MONTH_DAY);
dt->tm_mday = bcd2bin(tmp);
tmp = v3020_get_reg(chip, V3020_MONTH);
dt->tm_mon = bcd2bin(tmp) - 1;
tmp = v3020_get_reg(chip, V3020_WEEK_DAY);
dt->tm_wday = bcd2bin(tmp);
tmp = v3020_get_reg(chip, V3020_YEAR);
dt->tm_year = bcd2bin(tmp)+100;
dev_dbg(dev, "\n%s : Read RTC values\n", __func__);
dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
return 0;
}
static int v3020_set_time(struct device *dev, struct rtc_time *dt)
{
struct v3020 *chip = dev_get_drvdata(dev);
dev_dbg(dev, "\n%s : Setting RTC values\n", __func__);
dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
/* Write all the values to ram... */
v3020_set_reg(chip, V3020_SECONDS, bin2bcd(dt->tm_sec));
v3020_set_reg(chip, V3020_MINUTES, bin2bcd(dt->tm_min));
v3020_set_reg(chip, V3020_HOURS, bin2bcd(dt->tm_hour));
v3020_set_reg(chip, V3020_MONTH_DAY, bin2bcd(dt->tm_mday));
v3020_set_reg(chip, V3020_MONTH, bin2bcd(dt->tm_mon + 1));
v3020_set_reg(chip, V3020_WEEK_DAY, bin2bcd(dt->tm_wday));
v3020_set_reg(chip, V3020_YEAR, bin2bcd(dt->tm_year % 100));
/* ...and set the clock. */
v3020_set_reg(chip, V3020_CMD_RAM2CLOCK, 0);
/* Compulab used this delay here. I dont know why,
* the datasheet does not specify a delay. */
/*mdelay(5);*/
return 0;
}
static const struct rtc_class_ops v3020_rtc_ops = {
.read_time = v3020_read_time,
.set_time = v3020_set_time,
};
static int rtc_probe(struct platform_device *pdev)
{
struct v3020_platform_data *pdata = dev_get_platdata(&pdev->dev);
struct v3020 *chip;
int retval;
int i;
chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
if (pdata->use_gpio)
chip->ops = &v3020_gpio_ops;
else
chip->ops = &v3020_mmio_ops;
retval = chip->ops->map_io(chip, pdev, pdata);
if (retval)
return retval;
/* Make sure the v3020 expects a communication cycle
* by reading 8 times */
for (i = 0; i < 8; i++)
chip->ops->read_bit(chip);
/* Test chip by doing a write/read sequence
* to the chip ram */
v3020_set_reg(chip, V3020_SECONDS, 0x33);
if (v3020_get_reg(chip, V3020_SECONDS) != 0x33) {
retval = -ENODEV;
goto err_io;
}
/* Make sure frequency measurement mode, test modes, and lock
* are all disabled */
v3020_set_reg(chip, V3020_STATUS_0, 0x0);
if (pdata->use_gpio)
dev_info(&pdev->dev, "Chip available at GPIOs "
"%d, %d, %d, %d\n",
chip->gpio[V3020_CS].gpio, chip->gpio[V3020_WR].gpio,
chip->gpio[V3020_RD].gpio, chip->gpio[V3020_IO].gpio);
else
dev_info(&pdev->dev, "Chip available at "
"physical address 0x%llx,"
"data connected to D%d\n",
(unsigned long long)pdev->resource[0].start,
chip->leftshift);
platform_set_drvdata(pdev, chip);
chip->rtc = devm_rtc_device_register(&pdev->dev, "v3020",
&v3020_rtc_ops, THIS_MODULE);
if (IS_ERR(chip->rtc)) {
retval = PTR_ERR(chip->rtc);
goto err_io;
}
return 0;
err_io:
chip->ops->unmap_io(chip);
return retval;
}
static int rtc_remove(struct platform_device *dev)
{
struct v3020 *chip = platform_get_drvdata(dev);
chip->ops->unmap_io(chip);
return 0;
}
static struct platform_driver rtc_device_driver = {
.probe = rtc_probe,
.remove = rtc_remove,
.driver = {
.name = "v3020",
},
};
module_platform_driver(rtc_device_driver);
MODULE_DESCRIPTION("V3020 RTC");
MODULE_AUTHOR("Raphael Assenat");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:v3020");
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