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Subject[PATCH 4.9 116/271] hwmon: (w83627hf) Use request_muxed_region for Super-IO accesses
Date
From: Guenter Roeck <linux@roeck-us.net>

[ Upstream commit e95fd518d05bfc087da6fcdea4900a57cfb083bd ]

Super-IO accesses may fail on a system with no or unmapped LPC bus.

Also, other drivers may attempt to access the LPC bus at the same time,
resulting in undefined behavior.

Use request_muxed_region() to ensure that IO access on the requested
address space is supported, and to ensure that access by multiple drivers
is synchronized.

Fixes: b72656dbc491 ("hwmon: (w83627hf) Stop using globals for I/O port numbers")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/w83627hf.c | 42 +++++++++++++++++++++++++++++++++++-----
1 file changed, 37 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/w83627hf.c b/drivers/hwmon/w83627hf.c
index 721295b9a0517..43c0f89cefdf0 100644
--- a/drivers/hwmon/w83627hf.c
+++ b/drivers/hwmon/w83627hf.c
@@ -130,17 +130,23 @@ superio_select(struct w83627hf_sio_data *sio, int ld)
outb(ld, sio->sioaddr + 1);
}

-static inline void
+static inline int
superio_enter(struct w83627hf_sio_data *sio)
{
+ if (!request_muxed_region(sio->sioaddr, 2, DRVNAME))
+ return -EBUSY;
+
outb(0x87, sio->sioaddr);
outb(0x87, sio->sioaddr);
+
+ return 0;
}

static inline void
superio_exit(struct w83627hf_sio_data *sio)
{
outb(0xAA, sio->sioaddr);
+ release_region(sio->sioaddr, 2);
}

#define W627_DEVID 0x52
@@ -1275,7 +1281,7 @@ static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
static int __init w83627hf_find(int sioaddr, unsigned short *addr,
struct w83627hf_sio_data *sio_data)
{
- int err = -ENODEV;
+ int err;
u16 val;

static __initconst char *const names[] = {
@@ -1287,7 +1293,11 @@ static int __init w83627hf_find(int sioaddr, unsigned short *addr,
};

sio_data->sioaddr = sioaddr;
- superio_enter(sio_data);
+ err = superio_enter(sio_data);
+ if (err)
+ return err;
+
+ err = -ENODEV;
val = force_id ? force_id : superio_inb(sio_data, DEVID);
switch (val) {
case W627_DEVID:
@@ -1641,9 +1651,21 @@ static int w83627thf_read_gpio5(struct platform_device *pdev)
struct w83627hf_sio_data *sio_data = dev_get_platdata(&pdev->dev);
int res = 0xff, sel;

- superio_enter(sio_data);
+ if (superio_enter(sio_data)) {
+ /*
+ * Some other driver reserved the address space for itself.
+ * We don't want to fail driver instantiation because of that,
+ * so display a warning and keep going.
+ */
+ dev_warn(&pdev->dev,
+ "Can not read VID data: Failed to enable SuperIO access\n");
+ return res;
+ }
+
superio_select(sio_data, W83627HF_LD_GPIO5);

+ res = 0xff;
+
/* Make sure these GPIO pins are enabled */
if (!(superio_inb(sio_data, W83627THF_GPIO5_EN) & (1<<3))) {
dev_dbg(&pdev->dev, "GPIO5 disabled, no VID function\n");
@@ -1674,7 +1696,17 @@ static int w83687thf_read_vid(struct platform_device *pdev)
struct w83627hf_sio_data *sio_data = dev_get_platdata(&pdev->dev);
int res = 0xff;

- superio_enter(sio_data);
+ if (superio_enter(sio_data)) {
+ /*
+ * Some other driver reserved the address space for itself.
+ * We don't want to fail driver instantiation because of that,
+ * so display a warning and keep going.
+ */
+ dev_warn(&pdev->dev,
+ "Can not read VID data: Failed to enable SuperIO access\n");
+ return res;
+ }
+
superio_select(sio_data, W83627HF_LD_HWM);

/* Make sure these GPIO pins are enabled */
--
2.20.1


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