Re: [PATCH v2] mailbox: pcc: Support HW-Reduced Communication Subspace Type 2

[Hoan Tran]

Hi Ashwin,

Thanks for your review !

On Tue, May 10, 2016 at 5:00 AM, Ashwin Chaugule
<ashwin.chaugule@xxxxxxxxxx> wrote:
> Hello,
>
> On 6 May 2016 at 14:38, Hoan Tran <hotran@xxxxxxx> wrote:
>> From: hotran <hotran@xxxxxxx>
>>
>> ACPI 6.1 has a PCC HW-Reduced Communication Subspace Type 2 intended for
>> use on HW-Reduce ACPI Platform, which requires read-modify-write sequence
>> to acknowledge doorbell interrupt. This patch provides the implementation
>> for the Communication Subspace Type 2.
>>
>> This patch depends on patch [1] which supports PCC subspace type 2 header
>> [1] https://lkml.org/lkml/2016/5/5/14
>>  - [PATCH v2 03/13] ACPICA: ACPI 6.1: Support for new PCCT subtable
>>
>> v2
>>  * Remove changes inside "actbl3.h". This file is taken care by ACPICA.
>>  * Parse both subspace type 1 and subspace type 2
>>  * Remove unnecessary variable initialization
>>  * ISR returns IRQ_NONE in case of error
>>
>> v1
>>  * Initial
>>
>> Signed-off-by: Hoan Tran <hotran@xxxxxxx>
>> ---
>>  drivers/mailbox/pcc.c | 395 +++++++++++++++++++++++++++++++++++++-------------
>>  1 file changed, 296 insertions(+), 99 deletions(-)
>>
>> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
>> index 043828d..58c9a67 100644
>> --- a/drivers/mailbox/pcc.c
>> +++ b/drivers/mailbox/pcc.c
>> @@ -59,6 +59,7 @@
>>  #include <linux/delay.h>
>>  #include <linux/io.h>
>>  #include <linux/init.h>
>> +#include <linux/interrupt.h>
>>  #include <linux/list.h>
>>  #include <linux/platform_device.h>
>>  #include <linux/mailbox_controller.h>
>> @@ -68,27 +69,179 @@
>>  #include "mailbox.h"
>>
>>  #define MAX_PCC_SUBSPACES      256
>> +#define MBOX_IRQ_NAME          "pcc-mbox"
>>
>> -static struct mbox_chan *pcc_mbox_channels;
>> +/**
>> + * PCC mailbox channel information
>> + *
>> + * @chan:      Pointer to mailbox communication channel
>> + * @pcc_doorbell_vaddr: PCC doorbell register address
>> + * @pcc_doorbell_ack_vaddr: PCC doorbell ack register address
>> + * @irq:       Interrupt number of the channel
>> + */
>> +struct pcc_mbox_chan {
>> +       struct mbox_chan        *chan;
>> +       void __iomem            *pcc_doorbell_vaddr;
>> +       void __iomem            *pcc_doorbell_ack_vaddr;
>> +       int                     irq;
>> +};
>>
>> -/* Array of cached virtual address for doorbell registers */
>> -static void __iomem **pcc_doorbell_vaddr;
>> +/**
>> + * PCC mailbox controller data
>> + *
>> + * @mb_ctrl:   Representation of the communication channel controller
>> + * @mbox_chan: Array of PCC mailbox channels of the controller
>> + * @chans:     Array of mailbox communication channels
>> + */
>> +struct pcc_mbox {
>> +       struct mbox_controller  mbox_ctrl;
>> +       struct pcc_mbox_chan    *mbox_chans;
>> +       struct mbox_chan        *chans;
>> +};
>> +
>> +static struct pcc_mbox pcc_mbox_ctx = {};
>
> Im missing the idea behind creating this structure. Are you
> registering multiple controllers somewhere?
No, I just want to use a structure to store all global variables into
>
>
> [...]
>
>>
>> @@ -357,24 +534,44 @@ static int __init acpi_pcc_probe(void)
>>         pcct_entry = (struct acpi_subtable_header *) (
>>                 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
>>
>> +       acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
>> +       if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
>> +               pcc_mbox_ctx.mbox_ctrl.txdone_irq = true;
>> +
>>         for (i = 0; i < count; i++) {
>>                 struct acpi_generic_address *db_reg;
>>                 struct acpi_pcct_hw_reduced *pcct_ss;
>> -               pcc_mbox_channels[i].con_priv = pcct_entry;
>> +
>> +               pcc_mbox_ctx.chans[i].con_priv = pcct_entry;
>> +               pcc_mbox_ctx.chans[i].mbox = &pcc_mbox_ctx.mbox_ctrl;
>> +
>> +               pcct_ss = (struct acpi_pcct_hw_reduced *) pcct_entry;
>> +
>> +               pcc_mbox_ctx.mbox_chans[i].chan = &pcc_mbox_ctx.chans[i];
>> +               if (pcc_mbox_ctx.mbox_ctrl.txdone_irq) {
>> +                       rc = pcc_parse_subspace_irq(&pcc_mbox_ctx.mbox_chans[i],
>> +                                                   pcct_ss);
>> +                       if (rc < 0)
>> +                               return rc;
>> +               }
>
> I think we should parse the remaining entries and register them if
> they are sane. Some other PCC clients can then continue to function.
I think, it could be an error of PCCT table and need to be returned.
>
>>
>>                 /* If doorbell is in system memory cache the virt address */
>>                 pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
>>                 db_reg = &pcct_ss->doorbell_register;
>> -               if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
>> -                       pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
>> +               if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
>> +                       pcc_mbox_ctx.mbox_chans[i].pcc_doorbell_vaddr =
>> +                                       acpi_os_ioremap(db_reg->address,
>>                                                         db_reg->bit_width/8);
>> +               }
>> +
>>                 pcct_entry = (struct acpi_subtable_header *)
>>                         ((unsigned long) pcct_entry + pcct_entry->length);
>>         }
>>
>> -       pcc_mbox_ctrl.num_chans = count;
>> +       pcc_mbox_ctx.mbox_ctrl.num_chans = count;
>>
>> -       pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
>> +       pr_info("Detected %d PCC Subspaces\n",
>> +               pcc_mbox_ctx.mbox_ctrl.num_chans);
>>
>>         return 0;
>>  }
>> @@ -394,12 +591,12 @@ static int pcc_mbox_probe(struct platform_device *pdev)
>>  {
>>         int ret = 0;
>>
>> -       pcc_mbox_ctrl.chans = pcc_mbox_channels;
>> -       pcc_mbox_ctrl.ops = &pcc_chan_ops;
>> -       pcc_mbox_ctrl.dev = &pdev->dev;
>> +       pcc_mbox_ctx.mbox_ctrl.chans = pcc_mbox_ctx.chans;
>> +       pcc_mbox_ctx.mbox_ctrl.ops = &pcc_chan_ops;
>> +       pcc_mbox_ctx.mbox_ctrl.dev = &pdev->dev;
>>
>>         pr_info("Registering PCC driver as Mailbox controller\n");
>> -       ret = mbox_controller_register(&pcc_mbox_ctrl);
>> +       ret = mbox_controller_register(&pcc_mbox_ctx.mbox_ctrl);
>
> That pcc_mbox_ctx usage everywhere seems questionable to me. But its
> also too early in the morning here. ;)
As the same with previous comments, I would like to move all global
variables into a structure

Thanks and Regards
Hoan
>
> Regards,
> Ashwin.

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