Re: [PATCH V2 09/10] i3c: mipi-i3c-hci-pci: Add support for Multi-Bus Instances

[Adrian Hunter <adrian.hunter@intel.com>]

On 11/12/2025 18:44, Frank Li wrote:
> On Thu, Dec 11, 2025 at 03:48:08PM +0200, Adrian Hunter wrote:
>> A MIPI I3C Host Controller with the Multi-Bus Instance capability supports
>> multiple I3C Buses (up to 15).
> with single hardware function (e.g. PCIe B/D/F).
> 
> ...
>> with one instance of the HCI Register Set
>> and one instance of I3C Bus Controller Logic for each I3C Bus, in a single
>> hardware function (e.g. PCIe B/D/F).
> 
> Each I3C bus have indepedent HCI register space and I3C Bus controller logic.
> 
>>
>> Create an MFD cell for each instance.  Use platform_data to pass the
>> instance's register set start address.
>>
>> MIPI I3C specification defines an Extended Capability to hold the offset
>> of each instance register set.  However parsing to find that information is
>> relatively complicated compared with just including it in the driver data.
>> Do that for now.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>> ---
>>
>>
>> Changes in V2:
>> 	Conversion to MFD split into separate patch
>> 	Simplify ID allocation / free
>> 	Correct use of __free()
>> 	Also define instance 0 in driver_data
>>
>>
>>  .../master/mipi-i3c-hci/mipi-i3c-hci-pci.c    | 63 +++++++++++++++----
>>  1 file changed, 50 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/i3c/master/mipi-i3c-hci/mipi-i3c-hci-pci.c b/drivers/i3c/master/mipi-i3c-hci/mipi-i3c-hci-pci.c
>> index 68088967942b..de1f71763786 100644
>> --- a/drivers/i3c/master/mipi-i3c-hci/mipi-i3c-hci-pci.c
>> +++ b/drivers/i3c/master/mipi-i3c-hci/mipi-i3c-hci-pci.c
>> @@ -19,10 +19,17 @@
>>  #include <linux/platform_device.h>
>>  #include <linux/pm_qos.h>
>>
>> +/*
>> + * There can up to 15 instances, but implementations have at most 2 at this
>> + * time.
>> + */
>> +#define INST_MAX 2
>> +
>>  struct mipi_i3c_hci_pci {
>>  	struct pci_dev *pci;
>>  	void __iomem *base;
>> -	int dev_id;
>> +	int dev_id[INST_MAX];
>> +	int dev_id_cnt;
>>  	const struct mipi_i3c_hci_pci_info *info;
>>  	void *private;
>>  };
>> @@ -30,6 +37,8 @@ struct mipi_i3c_hci_pci {
>>  struct mipi_i3c_hci_pci_info {
>>  	int (*init)(struct mipi_i3c_hci_pci *hci);
>>  	void (*exit)(struct mipi_i3c_hci_pci *hci);
>> +	u32 instance_offset[INST_MAX];
>> +	int instance_count;
>>  };
>>
>>  static DEFINE_IDA(mipi_i3c_hci_pci_ida);
>> @@ -177,53 +186,81 @@ static void intel_i3c_exit(struct mipi_i3c_hci_pci *hci)
>>  static const struct mipi_i3c_hci_pci_info intel_info = {
>>  	.init = intel_i3c_init,
>>  	.exit = intel_i3c_exit,
>> +	.instance_offset = {0},
>> +	.instance_count = 1,
> 
> just one instance? suppose at least 2, otherwise, not need this patch.

Adding multiple instances is in a separate patch

> 
>>  };
>>
>> +static void mipi_i3c_hci_pci_free_ids(struct mipi_i3c_hci_pci *hci)
>> +{
>> +	for (int i = 0; i < hci->dev_id_cnt; i++)
>> +		ida_free(&mipi_i3c_hci_pci_ida, hci->dev_id[i]);
>> +}
>> +
>> +static int mipi_i3c_hci_pci_alloc_ids(struct mipi_i3c_hci_pci *hci, int nr)
>> +{
>> +	for (int i = 0; i < nr; i++) {
>> +		hci->dev_id[i] = ida_alloc(&mipi_i3c_hci_pci_ida, GFP_KERNEL);
>> +		if (hci->dev_id[i]  < 0)
>> +			goto err_free_ids;
>> +		hci->dev_id_cnt = i + 1;
>> +	}
>> +
>> +	return 0;
>> +
>> +err_free_ids:
>> +	mipi_i3c_hci_pci_free_ids(hci);
>> +	return -ENOMEM;
> 
> You have to handle ida error, actually, it makes not big difference with
> mfd and add multi platform devices.

The ids have to be defined in any case.

MFD still handles:
	Setting the firmware node
	Deleting devices if 1 fails to create
	Removing all devices i.e. mfd_remove_devices()

> 
>> +}
>> +
>>  struct mipi_i3c_hci_pci_cell_data {
>>  	struct mipi_i3c_hci_platform_data pdata;
>>  	struct resource res;
>>  };
>>
>> -static void mipi_i3c_hci_pci_setup_cell(struct mipi_i3c_hci_pci *hci,
>> +static void mipi_i3c_hci_pci_setup_cell(struct mipi_i3c_hci_pci *hci, int idx,
>>  					struct mipi_i3c_hci_pci_cell_data *data,
>>  					struct mfd_cell *cell)
>>  {
>> -	data->pdata.base_regs = hci->base;
>> +	data->pdata.base_regs = hci->base + hci->info->instance_offset[idx];
>>
>>  	data->res = DEFINE_RES_IRQ(0);
>>
>>  	cell->name = "mipi-i3c-hci";
>> -	cell->id = hci->dev_id;
>> +	cell->id = hci->dev_id[idx];
>>  	cell->platform_data = &data->pdata;
>>  	cell->pdata_size = sizeof(data->pdata);
>>  	cell->num_resources = 1;
>>  	cell->resources = &data->res;
>>  }
>>
>> +#define mipi_i3c_hci_pci_alloc(x) kcalloc(hci->info->instance_count, sizeof(*(x)), GFP_KERNEL)
>> +
> 
> It is not good to hide hci in macro.
> 
> mipi_i3c_hci_pci_alloc(hci, x); or
> mipi_i3c_hci_pci_alloc(nr, x)
> 
>>  static int mipi_i3c_hci_pci_add_instances(struct mipi_i3c_hci_pci *hci)
>>  {
>> -	struct mipi_i3c_hci_pci_cell_data *data __free(kfree) = kzalloc(sizeof(*data), GFP_KERNEL);
>> -	struct mfd_cell *cells __free(kfree) = kzalloc(sizeof(*cells), GFP_KERNEL);
>> +	struct mipi_i3c_hci_pci_cell_data *data __free(kfree) = mipi_i3c_hci_pci_alloc(data);
>> +	struct mfd_cell *cells __free(kfree) = mipi_i3c_hci_pci_alloc(cells);
>>  	int irq = pci_irq_vector(hci->pci, 0);
>> +	int nr = hci->info->instance_count;
>>  	int ret;
>>
>>  	if (!cells || !data)
>>  		return -ENOMEM;
>>
>> -	hci->dev_id = ida_alloc(&mipi_i3c_hci_pci_ida, GFP_KERNEL);
>> -	if (hci->dev_id < 0)
>> -		return hci->dev_id;
>> +	ret = mipi_i3c_hci_pci_alloc_ids(hci, nr);
>> +	if (ret)
>> +		return ret;
>>
>> -	mipi_i3c_hci_pci_setup_cell(hci, data, cells);
>> +	for (int i = 0; i < nr; i++)
>> +		mipi_i3c_hci_pci_setup_cell(hci, i, data + i, cells + i);
>>
>> -	ret = mfd_add_devices(&hci->pci->dev, 0, cells, 1, NULL, irq, NULL);
>> +	ret = mfd_add_devices(&hci->pci->dev, 0, cells, nr, NULL, irq, NULL);
>>  	if (ret)
>>  		goto err_free_ids;
>>
>>  	return 0;
>>
>>  err_free_ids:
>> -	ida_free(&mipi_i3c_hci_pci_ida, hci->dev_id);
>> +	mipi_i3c_hci_pci_free_ids(hci);
>>  	return ret;
>>  }
>>
>> @@ -281,7 +318,7 @@ static void mipi_i3c_hci_pci_remove(struct pci_dev *pci)
>>  		hci->info->exit(hci);
>>
>>  	mfd_remove_devices(&pci->dev);
>> -	ida_free(&mipi_i3c_hci_pci_ida, hci->dev_id);
>> +	mipi_i3c_hci_pci_free_ids(hci);
>>  }
>>
>>  static const struct pci_device_id mipi_i3c_hci_pci_devices[] = {
>> --
>> 2.51.0
>>
>>
>> --
>> linux-i3c mailing list
>> linux-i3c@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-i3c


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