On Sun, Nov 01, 2015 at 05:32:08PM +0100, Christian Fetzer wrote:
> The SB800 chipset supports a multiplexed main SMBus controller with
> four ports. The multiplexed ports share the same SMBus address and
> register set. The port is selected by bits 2:1 of the smb_en register
> (0x2C).
>
> Only one port can be active at any point in time therefore a mutex is
> needed in order to synchronize access.
>
> Tested on HP ProLiant MicroServer G7 N54L (where this patch adds
> support to access sensor data from the w83795adg).
>
> Cc: Thomas Brandon <tbrando...@gmail.com>
> Cc: Eddi De Pieri <e...@depieri.net>
> Signed-off-by: Christian Fetzer <fetzer...@gmail.com>
Few minor comments, see below.
Regardless of them,
Reviewed-by: Mika Westerberg <mika.westerb...@linux.intel.com>
> ---
> drivers/i2c/busses/i2c-piix4.c | 102
> +++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 97 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index d866b58..54f8af5 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -23,6 +23,9 @@
>
> Note: we assume there can only be one device, with one or more
> SMBus interfaces.
> + The device can register multiple i2c_adapters (up to PIIX4_MAX_ADAPTERS).
> + For devices supporting multiple ports the i2c_adapter should provide
> + an i2c_algorithm to access them.
> */
>
> #include <linux/module.h>
> @@ -37,6 +40,7 @@
> #include <linux/dmi.h>
> #include <linux/acpi.h>
> #include <linux/io.h>
> +#include <linux/mutex.h>
>
>
> /* PIIX4 SMBus address offsets */
> @@ -126,10 +130,12 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
> };
>
> /* SB800 globals */
> +DEFINE_MUTEX(piix4_mutex_sb800);
> static unsigned short piix4_smb_idx_sb800;
>
> struct i2c_piix4_adapdata {
> unsigned short smba;
> + unsigned short port;
> };
>
> static int piix4_setup(struct pci_dev *PIIX4_dev,
> @@ -309,6 +315,8 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
> else
> dev_dbg(&PIIX4_dev->dev, "Using SMI# for SMBus\n");
>
> + mutex_init(&piix4_mutex_sb800);
> +
> dev_info(&PIIX4_dev->dev,
> "SMBus Host Controller at 0x%x, revision %d\n",
> piix4_smba, i2ccfg >> 4);
> @@ -523,6 +531,42 @@ static s32 piix4_access(struct i2c_adapter * adap, u16
> addr,
> return 0;
> }
>
> +/* Handles access to multiple SMBus ports on the SB800.
> + * The port is selected by bits 2:1 of the smb_en register (0x2C).
> + * Returns negative errno on error.
Block comments look like:
/*
* Handles access to multiple...
*
> + *
> + * Note: The selected port must be returned to the initial selection to avoid
> + * problems on certain systems.
> + */
> +static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
> + unsigned short flags, char read_write,
> + u8 command, int size, union i2c_smbus_data *data)
> +{
> + struct i2c_piix4_adapdata *adapdata = i2c_get_adapdata(adap);
> + u8 smba_en_lo, smb_en = 0x2c;
> + u8 port;
> + int retval;
> +
> + mutex_lock(&piix4_mutex_sb800);
> +
> + outb_p(smb_en, piix4_smb_idx_sb800);
> + smba_en_lo = inb_p(piix4_smb_idx_sb800 + 1);
> +
> + port = adapdata->port;
> + if ((smba_en_lo & 6) != (port << 1))
> + outb_p((smba_en_lo & ~6) | (port << 1),
> + piix4_smb_idx_sb800 + 1);
> +
> + retval = piix4_access(adap, addr, flags, read_write,
> + command, size, data);
> +
> + outb_p(smba_en_lo, piix4_smb_idx_sb800 + 1);
> +
> + mutex_unlock(&piix4_mutex_sb800);
> +
> + return retval;
> +}
> +
> static u32 piix4_func(struct i2c_adapter *adapter)
> {
> return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
> @@ -535,6 +579,11 @@ static const struct i2c_algorithm smbus_algorithm = {
> .functionality = piix4_func,
> };
>
> +static const struct i2c_algorithm piix4_smbus_algorithm_sb800 = {
> + .smbus_xfer = piix4_access_sb800,
> + .functionality = piix4_func,
> +};
> +
> static const struct pci_device_id piix4_ids[] = {
> { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3) },
> { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82443MX_3) },
> @@ -610,6 +659,42 @@ static int piix4_add_adapter(struct pci_dev *dev,
> unsigned short smba,
> return 0;
> }
>
> +static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba)
> +{
> + unsigned short port;
> + int retval;
> + struct i2c_piix4_adapdata *adapdata;
> +
> + for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
> + retval = piix4_add_adapter(dev, smba,
> + &piix4_main_adapters[port]);
> + if (retval < 0)
> + goto error;
> +
> + piix4_main_adapters[port]->algo = &piix4_smbus_algorithm_sb800;
> +
> + adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
> + adapdata->port = port;
> + }
> +
> + return retval;
> +
> +error:
> + dev_err(&dev->dev, "Error setting up SB800 adapters. "
> + "Unregistering all adapters!\n");
You don't need to split the error string here. It makes grepping the
error messages harder. Just write it like:
dev_err(&dev->dev, "Error setting up SB800 adapters. Unregistering all
adapters!\n");
You may want to shorten the error message, though.
> + for (port--; port >= 0; port--) {
> + adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
> + if (adapdata->smba) {
> + i2c_del_adapter(piix4_main_adapters[port]);
> + kfree(adapdata);
> + kfree(piix4_main_adapters[port]);
> + piix4_main_adapters[port] = NULL;
> + }
> + }
> +
> + return retval;
> +}
> +
> static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
> {
> unsigned short smba_idx = 0xcd6;
> @@ -629,19 +714,26 @@ static int piix4_probe(struct pci_dev *dev, const
> struct pci_device_id *id)
>
> /* base address location etc changed in SB800 */
> retval = piix4_setup_sb800(dev, id, 0);
> + if (retval < 0)
> + return retval;
> +
> + /* Try to register multiplexed main SMBus adapter,
> + * give up if we can't */
> + retval = piix4_add_adapters_sb800(dev, retval);
> } else {
> retval = piix4_setup(dev, id);
> + if (retval < 0)
> + return retval;
> +
> + /* Try to register main SMBus adapter, give up if we can't */
> + retval = piix4_add_adapter(dev, retval,
> + &piix4_main_adapters[0]);
> }
>
> /* If no main SMBus found, give up */
> if (retval < 0)
> return retval;
>
> - /* Try to register main SMBus adapter, give up if we can't */
> - retval = piix4_add_adapter(dev, retval, &piix4_main_adapters[0]);
> - if (retval < 0)
> - return retval;
> -
> /* Check for auxiliary SMBus on some AMD chipsets */
> retval = -ENODEV;
>
> --
> 1.9.1
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