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Date: Tue, 12 Jun 2012 14:10:35 +0200
From: Jean Delvare <khali@...ux-fr.org>
To: Andrew Armenia <andrew@...uaredlabs.com>
Cc: Ben Dooks <ben-linux@...ff.org>,
Wolfram Sang <w.sang@...gutronix.de>,
linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] i2c-piix4: separate registration and probing code
On Mon, 4 Jun 2012 21:49:23 -0400, Andrew Armenia wrote:
> Some chipsets have multiple sets of SMBus registers each controlling a
> separate SMBus. Supporting these chipsets properly will require registering
> multiple I2C adapters for one piix4.
>
> The code to initialize and register the i2c_adapter structure has been
> separated from piix4_probe and allows registration of a piix4 adapter
> given its base address. Note that the i2c_adapter and piix4_adapdata
> structures are now dynamically allocated.
>
> Signed-off-by: Andrew Armenia <andrew@...uaredlabs.com>
> ---
> drivers/i2c/busses/i2c-piix4.c | 79 ++++++++++++++++++++++++++--------------
> 1 file changed, 51 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index 7a5889c..8a87b3f 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -480,16 +480,6 @@ static const struct i2c_algorithm smbus_algorithm = {
> .functionality = piix4_func,
> };
>
> -static struct i2c_adapter piix4_adapter = {
> - .owner = THIS_MODULE,
> - .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
> - .algo = &smbus_algorithm,
> -};
> -
> -static struct i2c_piix4_adapdata piix4_adapter_data = {
> - .smba = 0,
> -};
> -
> static DEFINE_PCI_DEVICE_TABLE(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) },
> @@ -514,6 +504,48 @@ static DEFINE_PCI_DEVICE_TABLE(piix4_ids) = {
>
> MODULE_DEVICE_TABLE (pci, piix4_ids);
>
> +static struct i2c_adapter *piix4_main_adapter;
> +
> +/* register piix4 I2C adapter at the given base address */
> +static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
> + struct i2c_adapter **padap) {
Called from a __devinit function, could be made __devinit.
> + struct i2c_adapter *piix4_adapter;
> + struct i2c_piix4_adapdata *piix4_adapdata;
It would be pleasant to use the same names here and in
piix4_adap_remove(), for consistency.
> + int retval;
> +
> + piix4_adapter = kmalloc(sizeof(*piix4_adapter), GFP_KERNEL);
> + memset(piix4_adapter, 0, sizeof(*piix4_adapter));
Please use kzalloc. Furthermore, k*alloc() can theoretically fail, so
you have to check for this unlikely case and handle it gracefully.
> + piix4_adapter->owner = THIS_MODULE;
> + piix4_adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
> + piix4_adapter->algo = &smbus_algorithm;
> +
> + piix4_adapdata = kmalloc(sizeof(*piix4_adapdata), GFP_KERNEL);
> + memset(piix4_adapdata, 0, sizeof(*piix4_adapdata));
Same here.
> + piix4_adapdata->smba = smba;
> +
> + /* set up the sysfs linkage to our parent device */
> + piix4_adapter->dev.parent = &dev->dev;
> +
> + snprintf(piix4_adapter->name, sizeof(piix4_adapter->name),
> + "SMBus PIIX4 adapter at %04x", smba);
> +
> + piix4_adapdata->smba = smba;
You already did that a few lines above.
> +
> + i2c_set_adapdata(piix4_adapter, piix4_adapdata);
> +
> + retval = i2c_add_adapter(piix4_adapter);
> + if (retval) {
> + dev_err(&dev->dev, "Couldn't register adapter!\n");
> + release_region(smba, SMBIOSIZE);
> + kfree(piix4_adapdata);
> + kfree(piix4_adapter);
> + }
> +
> + *padap = piix4_adapter;
It's pointless do to that in the error case.
> +
> + return retval;
> +}
> +
> static int __devinit piix4_probe(struct pci_dev *dev,
> const struct pci_device_id *id)
> {
> @@ -532,25 +564,10 @@ static int __devinit piix4_probe(struct pci_dev *dev,
> if (retval)
> return retval;
>
> - /* set up the sysfs linkage to our parent device */
> - piix4_adapter.dev.parent = &dev->dev;
> -
> - snprintf(piix4_adapter.name, sizeof(piix4_adapter.name),
> - "SMBus PIIX4 adapter at %04x", smba);
> -
> - piix4_adapter_data.smba = smba;
> -
> - i2c_set_adapdata(&piix4_adapter, &piix4_adapter_data);
> -
> - if ((retval = i2c_add_adapter(&piix4_adapter))) {
> - dev_err(&dev->dev, "Couldn't register adapter!\n");
> - release_region(smba, SMBIOSIZE);
> - piix4_adapter_data.smba = 0;
> - }
> -
> - return retval;
> + return piix4_add_adapter(dev, smba, &piix4_main_adapter);
> }
>
> +/* Remove the adapter and its associated IO region */
> static void piix4_adap_remove(struct i2c_adapter *adap)
> {
> struct i2c_piix4_adapdata *adapdata;
> @@ -561,11 +578,17 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
> release_region(adapdata->smba, SMBIOSIZE);
> adapdata->smba = 0;
This one can go away, no point in cleaning up a structure you're about
to free.
> }
> +
> + kfree(adapdata);
> + kfree(adap);
> }
>
> static void __devexit piix4_remove(struct pci_dev *dev)
> {
> - piix4_adap_remove(&piix4_adapter);
> + if (piix4_main_adapter) {
> + piix4_adap_remove(piix4_main_adapter);
> + piix4_main_adapter = NULL;
> + }
> }
>
> static struct pci_driver piix4_driver = {
--
Jean Delvare
--
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