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    Subject[PATCH 4.19 309/639] 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 8ac89d0781ccc..a575e1cdb81a8 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
    @@ -1278,7 +1284,7 @@ static DEVICE_ATTR_RO(name);
    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[] = {
    @@ -1290,7 +1296,11 @@ 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:
    @@ -1644,9 +1654,21 @@ 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");
    @@ -1677,7 +1699,17 @@ 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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