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Subject[PATCH linux v5 2/3] drivers: w1: refactor w1_slave_show to make the temp reading functionality separate
Date
Inside the w1_slave_show function refactor the code to read the temp
into a separate function.

Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@google.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
---
v2
- made changes to support hwmon_device_register_with_info mentioned by Guenter.

v3
- used IS_REACHABLE(CONFIG_HWMON).
- removed hwmon device first before removing slave.

v4
- moved && to be in the previous line.

drivers/w1/slaves/w1_therm.c | 82 +++++++++++++++++++++++++++-----------------
1 file changed, 51 insertions(+), 31 deletions(-)

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index 82611f197b0a..64e6a8f38410 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -64,6 +64,12 @@ struct w1_therm_family_data {
atomic_t refcnt;
};

+struct therm_info {
+ u8 rom[9];
+ u8 crc;
+ u8 verdict;
+};
+
/* return the address of the refcnt in the family data */
#define THERM_REFCNT(family_data) \
(&((struct w1_therm_family_data *)family_data)->refcnt)
@@ -427,33 +433,31 @@ static ssize_t w1_slave_store(struct device *device,
return ret ? : size;
}

-static ssize_t w1_slave_show(struct device *device,
- struct device_attribute *attr, char *buf)
+static ssize_t read_therm(struct device *device,
+ struct w1_slave *sl, struct therm_info *info)
{
- struct w1_slave *sl = dev_to_w1_slave(device);
struct w1_master *dev = sl->master;
- u8 rom[9], crc, verdict, external_power;
- int i, ret, max_trying = 10;
- ssize_t c = PAGE_SIZE;
+ u8 external_power;
+ int ret, max_trying = 10;
u8 *family_data = sl->family_data;

ret = mutex_lock_interruptible(&dev->bus_mutex);
if (ret != 0)
- goto post_unlock;
+ goto error;

- if (!sl->family_data) {
+ if (!family_data) {
ret = -ENODEV;
- goto pre_unlock;
+ goto mt_unlock;
}

/* prevent the slave from going away in sleep */
atomic_inc(THERM_REFCNT(family_data));
- memset(rom, 0, sizeof(rom));
+ memset(info->rom, 0, sizeof(info->rom));

while (max_trying--) {

- verdict = 0;
- crc = 0;
+ info->verdict = 0;
+ info->crc = 0;

if (!w1_reset_select_slave(sl)) {
int count = 0;
@@ -479,47 +483,69 @@ static ssize_t w1_slave_show(struct device *device,
sleep_rem = msleep_interruptible(tm);
if (sleep_rem != 0) {
ret = -EINTR;
- goto post_unlock;
+ goto dec_refcnt;
}

ret = mutex_lock_interruptible(&dev->bus_mutex);
if (ret != 0)
- goto post_unlock;
+ goto dec_refcnt;
} else if (!w1_strong_pullup) {
sleep_rem = msleep_interruptible(tm);
if (sleep_rem != 0) {
ret = -EINTR;
- goto pre_unlock;
+ goto dec_refcnt;
}
}

if (!w1_reset_select_slave(sl)) {

w1_write_8(dev, W1_READ_SCRATCHPAD);
- count = w1_read_block(dev, rom, 9);
+ count = w1_read_block(dev, info->rom, 9);
if (count != 9) {
dev_warn(device, "w1_read_block() "
"returned %u instead of 9.\n",
count);
}

- crc = w1_calc_crc8(rom, 8);
+ info->crc = w1_calc_crc8(info->rom, 8);

- if (rom[8] == crc)
- verdict = 1;
+ if (info->rom[8] == info->crc)
+ info->verdict = 1;
}
}

- if (verdict)
+ if (info->verdict)
break;
}

+dec_refcnt:
+ atomic_dec(THERM_REFCNT(family_data));
+mt_unlock:
+ mutex_unlock(&dev->bus_mutex);
+error:
+ return ret;
+}
+
+static ssize_t w1_slave_show(struct device *device,
+ struct device_attribute *attr, char *buf)
+{
+ struct w1_slave *sl = dev_to_w1_slave(device);
+ struct therm_info info;
+ u8 *family_data = sl->family_data;
+ int ret, i;
+ ssize_t c = PAGE_SIZE;
+ u8 fid = sl->family->fid;
+
+ ret = read_therm(device, sl, &info);
+ if (ret)
+ return ret;
+
for (i = 0; i < 9; ++i)
- c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
+ c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", info.rom[i]);
c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
- crc, (verdict) ? "YES" : "NO");
- if (verdict)
- memcpy(family_data, rom, sizeof(rom));
+ info.crc, (info.verdict) ? "YES" : "NO");
+ if (info.verdict)
+ memcpy(family_data, info.rom, sizeof(info.rom));
else
dev_warn(device, "Read failed CRC check\n");

@@ -528,14 +554,8 @@ static ssize_t w1_slave_show(struct device *device,
((u8 *)family_data)[i]);

c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
- w1_convert_temp(rom, sl->family->fid));
+ w1_convert_temp(info.rom, fid));
ret = PAGE_SIZE - c;
-
-pre_unlock:
- mutex_unlock(&dev->bus_mutex);
-
-post_unlock:
- atomic_dec(THERM_REFCNT(family_data));
return ret;
}

--
2.13.2.932.g7449e964c-goog
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