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

[Frank Li <Frank.li@nxp.com>]

On Mon, Dec 15, 2025 at 07:37:39PM +0200, Adrian Hunter wrote:
> On 12/12/2025 19:46, Frank Li wrote:
> > On Fri, Dec 12, 2025 at 04:08:24PM +0200, Adrian Hunter wrote:
> >> 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
> >
> > Okay, commit message should mention it.
> >
> >>
> >>>
> >>>>  };
> >>>>
> >>>> +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()
> >
> > Actaully, why need remove previous failure device. assume support 15 device.
>
> Keeps things tidy.
>
> >
> > 7 success.  failure at 8 instance.
> >
> > I think it'd better keep 7 already success devices.  So 1-7 can work.
> > 8-15 can't work.
>
> If adding devices fails, the system is out of memory
> or in some catastrophic state, so there is no need to try to
> cater for that case.

Okay, I remembered system use defer probe to resolve dependence problem.
It is most likely all success if dependent device probed.

Go ahead, sorry for annoise.

Frnak
>
> >
> > It should be better than total 15 instances doesn't.
>
> Not necessarily.  If whole probe fails, the user might try again
> and succeed.
>
> >
> > Frank
> >
> >
> >>
> >>>
> >>>> +}
> >>>> +
> >>>>  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
> >>
> >>
> >> --
> >> linux-i3c mailing list
> >> linux-i3c@lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-i3c
>
>
> --
> linux-i3c mailing list
> linux-i3c@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-i3c

-- 
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c