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Message-ID: <CAFHUOYzWVQ0chPrYcPd+fzFww_a4atO6pdyyaNrKw2Pbg+LOJw@mail.gmail.com>
Date: Tue, 19 Apr 2016 13:40:13 -0700
From: Hoan Tran <hotran@....com>
To: Alexey Klimov <alexey.klimov@....com>
Cc: Jassi Brar <jassisinghbrar@...il.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>,
Robert Moore <robert.moore@...el.com>,
Lv Zheng <lv.zheng@...el.com>, linux-kernel@...r.kernel.org,
linux-acpi@...r.kernel.org, devel@...ica.org, Loc Ho <lho@....com>,
Duc Dang <dhdang@....com>
Subject: Re: [PATCH] mailbox: pcc: Support HW-Reduced Communication Subspace
Type 2
Hi Alexey,
On Tue, Apr 19, 2016 at 12:02 PM, Alexey Klimov <alexey.klimov@....com> wrote:
> Hi Hoan,
>
> On Tue, Apr 5, 2016 at 11:14 PM, hotran <hotran@....com> wrote:
>> ACPI 6.1 has a 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.
>>
>> Signed-off-by: Hoan Tran <hotran@....com>
>> ---
>> drivers/mailbox/pcc.c | 384 +++++++++++++++++++++++++++++++++++++-------------
>> include/acpi/actbl3.h | 8 +-
>> 2 files changed, 294 insertions(+), 98 deletions(-)
>>
>> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
>> index 0ddf638..4ed8153 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 +69,178 @@
>> #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 = {};
>>
>> -static struct mbox_controller pcc_mbox_ctrl = {};
>> /**
>> * get_pcc_channel - Given a PCC subspace idx, get
>> - * the respective mbox_channel.
>> + * the respective pcc mbox_channel.
>> * @id: PCC subspace index.
>> *
>> * Return: ERR_PTR(errno) if error, else pointer
>> - * to mbox channel.
>> + * to pcc mbox channel.
>> */
>> -static struct mbox_chan *get_pcc_channel(int id)
>> +static struct pcc_mbox_chan *get_pcc_channel(int id)
>> {
>> - if (id < 0 || id > pcc_mbox_ctrl.num_chans)
>> + if (id < 0 || id > pcc_mbox_ctx.mbox_ctrl.num_chans)
>> return ERR_PTR(-ENOENT);
>>
>> - return &pcc_mbox_channels[id];
>> + return &pcc_mbox_ctx.mbox_chans[id];
>> +}
>> +
>> +/*
>> + * PCC can be used with perf critical drivers such as CPPC
>> + * So it makes sense to locally cache the virtual address and
>> + * use it to read/write to PCC registers such as doorbell register
>> + *
>> + * The below read_register and write_registers are used to read and
>> + * write from perf critical registers such as PCC doorbell register
>> + */
>> +static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
>> +{
>> + int ret_val = 0;
>> +
>> + switch (bit_width) {
>> + case 8:
>> + *val = readb(vaddr);
>> + break;
>> + case 16:
>> + *val = readw(vaddr);
>> + break;
>> + case 32:
>> + *val = readl(vaddr);
>> + break;
>> + case 64:
>> + *val = readq(vaddr);
>> + break;
>> + default:
>> + pr_debug("Error: Cannot read register of %u bit width",
>> + bit_width);
>> + ret_val = -EFAULT;
>> + break;
>> + }
>> + return ret_val;
>> +}
>> +
>> +static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
>> +{
>> + int ret_val = 0;
>> +
>> + switch (bit_width) {
>> + case 8:
>> + writeb(val, vaddr);
>> + break;
>> + case 16:
>> + writew(val, vaddr);
>> + break;
>> + case 32:
>> + writel(val, vaddr);
>> + break;
>> + case 64:
>> + writeq(val, vaddr);
>> + break;
>> + default:
>> + pr_debug("Error: Cannot write register of %u bit width",
>> + bit_width);
>> + ret_val = -EFAULT;
>> + break;
>> + }
>> + return ret_val;
>> +}
>> +
>> +/**
>> + * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
>> + * @interrupt: GSI number.
>> + * @flags: interrupt flags
>> + *
>> + * Returns: a valid linux IRQ number on success
>> + * 0 or -EINVAL on failure
>> + */
>> +static int pcc_map_interrupt(u32 interrupt, u32 flags)
>> +{
>> + int trigger, polarity;
>> +
>> + if (!interrupt)
>> + return 0;
>> +
>> + trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
>> + : ACPI_LEVEL_SENSITIVE;
>> +
>> + polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
>> + : ACPI_ACTIVE_HIGH;
>> +
>> + return acpi_register_gsi(NULL, interrupt, trigger, polarity);
>> +}
>> +
>> +/**
>> + * pcc_mbox_irq - PCC mailbox interrupt handler
>> + */
>> +static irqreturn_t pcc_mbox_irq(int irq, void *id)
>> +{
>> + struct acpi_generic_address *doorbell_ack;
>> + struct acpi_pcct_hw_reduced *pcct_ss;
>> + struct pcc_mbox_chan *pcc_chan = id;
>> + u64 doorbell_ack_preserve;
>> + struct mbox_chan *chan;
>> + u64 doorbell_ack_write;
>> + u64 doorbell_ack_val;
>> + int ret = 0;
>
> Could you please check that you really need this initialization?
OK, will remove it
>
>> + chan = pcc_chan->chan;
>> + pcct_ss = chan->con_priv;
>> +
>> + /* Clear interrupt status */
>> + if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
>> + doorbell_ack = &pcct_ss->doorbell_ack_register;
>> + doorbell_ack_preserve = pcct_ss->ack_preserve_mask;
>> + doorbell_ack_write = pcct_ss->ack_write_mask;
>> +
>> + ret = read_register(pcc_chan->pcc_doorbell_ack_vaddr,
>> + &doorbell_ack_val,
>> + doorbell_ack->bit_width);
>> + if (ret)
>> + return ret;
>> +
>> + ret = write_register(pcc_chan->pcc_doorbell_ack_vaddr,
>> + (doorbell_ack_val & doorbell_ack_preserve)
>> + | doorbell_ack_write,
>> + doorbell_ack->bit_width);
>> + if (ret)
>> + return ret;
>
> Could you please check that really need to return -EFAULT here in case of error?
> Looking through irqreturn values it looks like IRQ_NONE is more proper value.
OK, change to return IRQ_NONE
>
>
>> + }
>> +
>> + mbox_chan_received_data(chan, NULL);
>> +
>> + return IRQ_HANDLED;
>> }
>>
>
> [...]
>
>> /**
>> + * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
>> + * There should be one entry per PCC client.
>> + * @mbox_chans: Pointer to the PCC mailbox channel data
>> + * @pcct_ss: Pointer to the ACPI subtable header under the PCCT.
>> + *
>> + * Return: 0 for Success, else errno.
>> + *
>> + * This gets called for each entry in the PCC table.
>> + */
>> +static int pcc_parse_subspace_irq(struct pcc_mbox_chan *mbox_chans,
>> + struct acpi_pcct_hw_reduced *pcct_ss)
>> +{
>> + mbox_chans->irq = pcc_map_interrupt(pcct_ss->doorbell_interrupt,
>> + (u32)pcct_ss->flags);
>> + if (mbox_chans->irq <= 0) {
>> + pr_err("PCC GSI %d not registered\n",
>> + pcct_ss->doorbell_interrupt);
>> + return -EINVAL;
>> + }
>> +
>> + if (pcct_ss->header.type
>> + == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
>> + mbox_chans->pcc_doorbell_ack_vaddr = acpi_os_ioremap(
>> + pcct_ss->doorbell_ack_register.address,
>> + pcct_ss->doorbell_ack_register.bit_width / 8);
>> + if (!mbox_chans->pcc_doorbell_ack_vaddr) {
>> + pr_err("Failed to ioremap PCC ACK register\n");
>> + return -ENOMEM;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
>> *
>> * Return: 0 for Success, else errno.
>> @@ -316,7 +479,8 @@ static int __init acpi_pcc_probe(void)
>> acpi_size pcct_tbl_header_size;
>> struct acpi_table_header *pcct_tbl;
>> struct acpi_subtable_header *pcct_entry;
>> - int count, i;
>> + struct acpi_table_pcct *acpi_pcct_tbl;
>> + int count, i, rc;
>> acpi_status status = AE_OK;
>>
>> /* Search for PCCT */
>> @@ -335,21 +499,29 @@ static int __init acpi_pcc_probe(void)
>> parse_pcc_subspace, MAX_PCC_SUBSPACES);
>>
>> if (count <= 0) {
>> + count = acpi_table_parse_entries(ACPI_SIG_PCCT,
>> + sizeof(struct acpi_table_pcct),
>> + ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2,
>> + parse_pcc_subspace, MAX_PCC_SUBSPACES);
>> + }
>> +
>> + if (count <= 0) {
>
> Do I understand this change correctly: in case type1 is present code flow doesn't try to parse type2 tables?
> Is presence of both type2 and type1 prohibited by specs?
Yes, it should parse all the subspace types then return error if
subspace count is <= 0.
Thanks and Regards
Hoan
>
>> pr_err("Error parsing PCC subspaces from PCCT\n");
>> return -EINVAL;
>> }
>
> [...]
>
> Best regards,
> Alexey
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