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

Ashwin Chaugule
2016-05-10T12:01:22Z

Hello,

On 6 May 2016 at 14:38, Hoan Tran <hotran@apm.com> wrote:
> From: hotran <hotran@apm.com>
>
> 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@apm.com>
> ---
> 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?

[...]

>
> @@ -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.

>
> /* 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. ;)

Regards,
Ashwin.