Re: [PATCH 3/5] i2c: piix4: Add ACPI support for ASF SMBus device

[Shyam Sundar S K <Shyam-sundar.S-k@amd.com>]

+Andy (this has some ACPI handling that adds AMD ASF support to the
existing piix4 driver for SMBus)

On 8/22/2024 19:51, Shyam Sundar S K wrote:
> The AMD ASF controller is presented to the operating system as an ACPI
> device. The piix4 driver can obtain the ASF handle through ACPI to
> retrieve information about the ASF controller's attributes, such as the
> ASF address space and interrupt number, and to handle ASF interrupts.
> 
> Currently, the piix4 driver assumes that a specific port address is
> designated for AUX operations. However, with the introduction of ASF, the
> same port address may also be used by the ASF controller. Therefore, a
> check needs to be added to ensure that if ASF is advertised and enabled in
> ACPI, the AUX port is not set up.
> 
> Co-developed-by: Sanket Goswami <Sanket.Goswami@amd.com>
> Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
> ---
>  drivers/i2c/busses/i2c-piix4.c | 161 ++++++++++++++++++++++++++++++++-
>  1 file changed, 160 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index a44b53dd4dd7..00fc641e6277 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -121,6 +121,8 @@
>  #define SB800_PIIX4_FCH_PM_ADDR			0xFED80300
>  #define SB800_PIIX4_FCH_PM_SIZE			8
>  #define SB800_ASF_BLOCK_MAX_BYTES		72
> +#define SB800_ASF_ERROR_STATUS			0xE
> +#define SB800_ASF_ACPI_PATH			"\\_SB.ASFC"
>  
>  /* insmod parameters */
>  
> @@ -185,6 +187,11 @@ struct sb800_mmio_cfg {
>  	bool use_mmio;
>  };
>  
> +struct sb800_asf_data {
> +	unsigned short addr;
> +	int irq;
> +};
> +
>  enum piix4_algo {
>  	SMBUS_SB800,
>  	SMBUS_LEGACY,
> @@ -201,6 +208,8 @@ struct i2c_piix4_adapdata {
>  	struct sb800_mmio_cfg mmio_cfg;
>  	u8 algo_select;
>  	struct i2c_client *slave;
> +	bool is_asf;
> +	struct delayed_work work_buf;
>  };
>  
>  static int piix4_sb800_region_request(struct device *dev,
> @@ -909,6 +918,66 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
>  	return retval;
>  }
>  
> +static void sb800_asf_process_slave(struct work_struct *work)
> +{
> +	struct i2c_piix4_adapdata *adapdata = container_of(work, struct i2c_piix4_adapdata,
> +							   work_buf.work);
> +	unsigned short piix4_smba = adapdata->smba;
> +	u8 data[SB800_ASF_BLOCK_MAX_BYTES];
> +	u8 bank, reg, cmd;
> +	u8 len, val = 0;
> +	int i;
> +
> +	/* Read slave status register */
> +	reg = inb_p(ASFSLVSTA);
> +
> +	/* Check if no error bits are set in slave status register */
> +	if (!(reg & SB800_ASF_ERROR_STATUS)) {
> +		/* Read data bank */
> +		reg = inb_p(ASFDATABNKSEL);
> +		bank = (reg & BIT(3)) >> 3;
> +
> +		/* Set read data bank */
> +		if (bank) {
> +			reg = reg | BIT(4);
> +			reg = reg & (~BIT(3));
> +		} else {
> +			reg = reg & (~BIT(4));
> +			reg = reg & (~BIT(2));
> +		}
> +
> +		/* Read command register */
> +		outb_p(reg, ASFDATABNKSEL);
> +		cmd = inb_p(ASFINDEX);
> +		len = inb_p(ASFDATARWPTR);
> +		for (i = 0; i < len; i++)
> +			data[i] = inb_p(ASFINDEX);
> +
> +		/* Clear data bank status */
> +		if (bank) {
> +			reg = reg | BIT(3);
> +			outb_p(reg, ASFDATABNKSEL);
> +		} else {
> +			reg = reg | BIT(2);
> +			outb_p(reg, ASFDATABNKSEL);
> +		}
> +	} else {
> +		/* Set bank as full */
> +		reg = reg | (BIT(3) | BIT(2));
> +		outb_p(reg, ASFDATABNKSEL);
> +	}
> +
> +	outb_p(0, ASFSETDATARDPTR);
> +	if (!(cmd & BIT(0))) {
> +		i2c_slave_event(adapdata->slave, I2C_SLAVE_WRITE_REQUESTED, &val);
> +		for (i = 0; i < len; i++) {
> +			val = data[i];
> +			i2c_slave_event(adapdata->slave, I2C_SLAVE_WRITE_RECEIVED, &val);
> +		}
> +		i2c_slave_event(adapdata->slave, I2C_SLAVE_STOP, &val);
> +	}
> +}
> +
>  static void sb800_asf_update_bits(unsigned short piix4_smba, u8 bit, unsigned long offset, bool set)
>  {
>  	unsigned long reg;
> @@ -1195,6 +1264,86 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
>  	return 0;
>  }
>  
> +static irqreturn_t sb800_asf_irq_handler(int irq, void *ptr)
> +{
> +	struct i2c_piix4_adapdata *adapdata = (struct i2c_piix4_adapdata *)ptr;
> +	unsigned short piix4_smba = adapdata->smba;
> +	u8 slave_int = inb_p(ASFSTA);
> +
> +	if ((slave_int & BIT(6))) {
> +		/* Slave Interrupt */
> +		outb_p(slave_int | BIT(6), ASFSTA);
> +		schedule_delayed_work(&adapdata->work_buf, HZ);
> +	} else {
> +		/* Master Interrupt */
> +		sb800_asf_update_bits(piix4_smba, SB800_ASF_SLV_INTR, SMBHSTSTS, true);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static acpi_status sb800_asf_acpi_resource_cb(struct acpi_resource *resource, void *context)
> +{
> +	struct sb800_asf_data *data = context;
> +
> +	switch (resource->type) {
> +	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
> +		data->irq = resource->data.extended_irq.interrupts[0];
> +		break;
> +	case ACPI_RESOURCE_TYPE_IO:
> +		data->addr = resource->data.io.minimum;
> +		break;
> +	}
> +
> +	return AE_OK;
> +}
> +
> +static int sb800_asf_add_adap(struct pci_dev *dev)
> +{
> +	struct i2c_piix4_adapdata *adapdata;
> +	struct sb800_asf_data *data;
> +	acpi_status status;
> +	acpi_handle handle;
> +	int ret;
> +
> +	status = acpi_get_handle(NULL, SB800_ASF_ACPI_PATH, &handle);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	data = devm_kzalloc(&dev->dev, sizeof(struct sb800_asf_data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	status = acpi_walk_resources(handle, METHOD_NAME__CRS, sb800_asf_acpi_resource_cb, data);
> +	if (ACPI_FAILURE(status))
> +		return -EINVAL;
> +
> +	if (!data->addr)
> +		return -EINVAL;
> +
> +	ret = piix4_add_adapter(dev, data->addr, SMBUS_ASF, piix4_adapter_count, false, 0,
> +				piix4_main_port_names_sb800[piix4_adapter_count],
> +				&piix4_main_adapters[piix4_adapter_count]);
> +	if (ret) {
> +		dev_err(&dev->dev, "Failed to add ASF adapter: %d\n", ret);
> +		return -ENODEV;
> +	}
> +
> +	adapdata = i2c_get_adapdata(piix4_main_adapters[piix4_adapter_count]);
> +	ret = devm_request_irq(&dev->dev, data->irq, sb800_asf_irq_handler, IRQF_SHARED,
> +			       "sb800_smbus_asf", adapdata);
> +	if (ret) {
> +		dev_err(&dev->dev, "Unable to request irq: %d for use\n", data->irq);
> +		return ret;
> +	}
> +
> +	INIT_DELAYED_WORK(&adapdata->work_buf, sb800_asf_process_slave);
> +	adapdata->is_asf = true;
> +	/* Increment the adapter count by 1 as ASF is added to the list */
> +	piix4_adapter_count += 1;
> +	return 1;
> +}
> +
>  static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba,
>  				    bool notify_imc)
>  {
> @@ -1243,6 +1392,7 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  {
>  	int retval;
>  	bool is_sb800 = false;
> +	bool is_asf = false;
>  
>  	if ((dev->vendor == PCI_VENDOR_ID_ATI &&
>  	     dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
> @@ -1279,6 +1429,10 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  		retval = piix4_add_adapters_sb800(dev, retval, notify_imc);
>  		if (retval < 0)
>  			return retval;
> +
> +		/* Check if ASF is enabled in SB800 */
> +		if (sb800_asf_add_adap(dev))
> +			is_asf = true;
>  	} else {
>  		retval = piix4_setup(dev, id);
>  		if (retval < 0)
> @@ -1308,7 +1462,9 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  	if (dev->vendor == PCI_VENDOR_ID_AMD &&
>  	    (dev->device == PCI_DEVICE_ID_AMD_HUDSON2_SMBUS ||
>  	     dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS)) {
> -		retval = piix4_setup_sb800(dev, id, 1);
> +		/* Do not setup AUX port if ASF is enabled */
> +		if (!is_asf)
> +			retval = piix4_setup_sb800(dev, id, 1);
>  	}
>  
>  	if (retval > 0) {
> @@ -1326,6 +1482,9 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
>  {
>  	struct i2c_piix4_adapdata *adapdata = i2c_get_adapdata(adap);
>  
> +	if (adapdata->is_asf)
> +		cancel_delayed_work_sync(&adapdata->work_buf);
> +
>  	if (adapdata->smba) {
>  		i2c_del_adapter(adap);
>  		if (adapdata->port == (0 << piix4_port_shift_sb800))