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Date: Tue, 31 May 2016 09:32:04 -0700
From: Hoan Tran <hotran@....com>
To: Jassi Brar <jassisinghbrar@...il.com>,
Ashwin Chaugule <ashwin.chaugule@...aro.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Robert Moore <robert.moore@...el.com>,
Alexey Klimov <alexey.klimov@....com>,
lkml <linux-kernel@...r.kernel.org>,
linux acpi <linux-acpi@...r.kernel.org>, Loc Ho <lho@....com>,
Duc Dang <dhdang@....com>, Hoan Tran <hotran@....com>
Subject: Re: [PATCH v3] mailbox: pcc: Support HW-Reduced Communication
Subspace type 2
Hi Ashwin,
Do you have any comments ?
Thanks
Hoan
On Thu, May 19, 2016 at 5:32 PM, Hoan Tran <hotran@....com> wrote:
> 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.
>
> v3
> * Remove 2 global structures
> * Correct parsing subspace type 1 and subspace type 2
>
> 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@....com>
> ---
> drivers/mailbox/pcc.c | 316 ++++++++++++++++++++++++++++++++++++++------------
> 1 file changed, 245 insertions(+), 71 deletions(-)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 043828d..c98bd94 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>
> @@ -68,11 +69,16 @@
> #include "mailbox.h"
>
> #define MAX_PCC_SUBSPACES 256
> +#define MBOX_IRQ_NAME "pcc-mbox"
>
> static struct mbox_chan *pcc_mbox_channels;
>
> /* Array of cached virtual address for doorbell registers */
> static void __iomem **pcc_doorbell_vaddr;
> +/* Array of cached virtual address for doorbell ack registers */
> +static void __iomem **pcc_doorbell_ack_vaddr;
> +/* Array of doorbell interrupts */
> +static int *pcc_doorbell_irq;
>
> static struct mbox_controller pcc_mbox_ctrl = {};
> /**
> @@ -91,6 +97,132 @@ static struct mbox_chan *get_pcc_channel(int id)
> return &pcc_mbox_channels[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 *p)
> +{
> + struct acpi_generic_address *doorbell_ack;
> + struct acpi_pcct_hw_reduced *pcct_ss;
> + struct mbox_chan *chan = p;
> + u64 doorbell_ack_preserve;
> + u64 doorbell_ack_write;
> + u64 doorbell_ack_val;
> + int ret;
> +
> + pcct_ss = chan->con_priv;
> +
> + mbox_chan_received_data(chan, NULL);
> +
> + if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
> + struct acpi_pcct_hw_reduced_type2 *pcct2_ss = chan->con_priv;
> + u32 id = chan - pcc_mbox_channels;
> +
> + doorbell_ack = &pcct2_ss->doorbell_ack_register;
> + doorbell_ack_preserve = pcct2_ss->ack_preserve_mask;
> + doorbell_ack_write = pcct2_ss->ack_write_mask;
> +
> + ret = read_register(pcc_doorbell_ack_vaddr[id],
> + &doorbell_ack_val,
> + doorbell_ack->bit_width);
> + if (ret)
> + return IRQ_NONE;
> +
> + ret = write_register(pcc_doorbell_ack_vaddr[id],
> + (doorbell_ack_val & doorbell_ack_preserve)
> + | doorbell_ack_write,
> + doorbell_ack->bit_width);
> + if (ret)
> + return IRQ_NONE;
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> /**
> * pcc_mbox_request_channel - PCC clients call this function to
> * request a pointer to their PCC subspace, from which they
> @@ -135,6 +267,18 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
> if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
> chan->txdone_method |= TXDONE_BY_ACK;
>
> + if (pcc_doorbell_irq[subspace_id] > 0) {
> + int rc;
> +
> + rc = devm_request_irq(dev, pcc_doorbell_irq[subspace_id],
> + pcc_mbox_irq, 0, MBOX_IRQ_NAME, chan);
> + if (unlikely(rc)) {
> + dev_err(dev, "failed to register PCC interrupt %d\n",
> + pcc_doorbell_irq[subspace_id]);
> + chan = ERR_PTR(rc);
> + }
> + }
> +
> spin_unlock_irqrestore(&chan->lock, flags);
>
> return chan;
> @@ -149,80 +293,30 @@ EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
> */
> void pcc_mbox_free_channel(struct mbox_chan *chan)
> {
> + u32 id = chan - pcc_mbox_channels;
> unsigned long flags;
>
> if (!chan || !chan->cl)
> return;
>
> + if (id >= pcc_mbox_ctrl.num_chans) {
> + pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n");
> + return;
> + }
> +
> spin_lock_irqsave(&chan->lock, flags);
> chan->cl = NULL;
> chan->active_req = NULL;
> if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
> chan->txdone_method = TXDONE_BY_POLL;
>
> + if (pcc_doorbell_irq[id] > 0)
> + devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan);
> +
> spin_unlock_irqrestore(&chan->lock, flags);
> }
> EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
>
> -/*
> - * 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_send_data - Called from Mailbox Controller code. Used
> @@ -296,8 +390,10 @@ static int parse_pcc_subspace(struct acpi_subtable_header *header,
> if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
> pcct_ss = (struct acpi_pcct_hw_reduced *) header;
>
> - if (pcct_ss->header.type !=
> - ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
> + if ((pcct_ss->header.type !=
> + ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE)
> + && (pcct_ss->header.type !=
> + ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2)) {
> pr_err("Incorrect PCC Subspace type detected\n");
> return -EINVAL;
> }
> @@ -307,6 +403,43 @@ static int parse_pcc_subspace(struct acpi_subtable_header *header,
> }
>
> /**
> + * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
> + * There should be one entry per PCC client.
> + * @id: PCC subspace index.
> + * @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(int id,
> + struct acpi_pcct_hw_reduced *pcct_ss)
> +{
> + pcc_doorbell_irq[id] = pcc_map_interrupt(pcct_ss->doorbell_interrupt,
> + (u32)pcct_ss->flags);
> + if (pcc_doorbell_irq[id] <= 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) {
> + struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
> +
> + pcc_doorbell_ack_vaddr[id] = acpi_os_ioremap(
> + pcct2_ss->doorbell_ack_register.address,
> + pcct2_ss->doorbell_ack_register.bit_width / 8);
> + if (!pcc_doorbell_ack_vaddr[id]) {
> + 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 +449,9 @@ 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;
> + int sum = 0;
> acpi_status status = AE_OK;
>
> /* Search for PCCT */
> @@ -333,37 +468,66 @@ static int __init acpi_pcc_probe(void)
> sizeof(struct acpi_table_pcct),
> ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
> parse_pcc_subspace, MAX_PCC_SUBSPACES);
> + sum += (count > 0)? 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);
> + sum += (count > 0)? count: 0;
>
> - if (count <= 0) {
> + if (sum == 0 || sum >= MAX_PCC_SUBSPACES) {
> pr_err("Error parsing PCC subspaces from PCCT\n");
> return -EINVAL;
> }
>
> pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
> - count, GFP_KERNEL);
> -
> + sum, GFP_KERNEL);
> if (!pcc_mbox_channels) {
> pr_err("Could not allocate space for PCC mbox channels\n");
> return -ENOMEM;
> }
>
> - pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
> + pcc_doorbell_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
> if (!pcc_doorbell_vaddr) {
> - kfree(pcc_mbox_channels);
> - return -ENOMEM;
> + rc = -ENOMEM;
> + goto err_free_mbox;
> + }
> +
> + pcc_doorbell_ack_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
> + if (!pcc_doorbell_ack_vaddr) {
> + rc = -ENOMEM;
> + goto err_free_db_vaddr;
> + }
> +
> + pcc_doorbell_irq = kcalloc(sum, sizeof(int), GFP_KERNEL);
> + if (!pcc_doorbell_irq) {
> + rc = -ENOMEM;
> + goto err_free_db_ack_vaddr;
> }
>
> /* Point to the first PCC subspace entry */
> pcct_entry = (struct acpi_subtable_header *) (
> (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
>
> - for (i = 0; i < count; i++) {
> + acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
> + if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
> + pcc_mbox_ctrl.txdone_irq = true;
> +
> + for (i = 0; i < sum; i++) {
> struct acpi_generic_address *db_reg;
> struct acpi_pcct_hw_reduced *pcct_ss;
> pcc_mbox_channels[i].con_priv = pcct_entry;
>
> + pcct_ss = (struct acpi_pcct_hw_reduced *) pcct_entry;
> +
> + if (pcc_mbox_ctrl.txdone_irq) {
> + rc = pcc_parse_subspace_irq(i, pcct_ss);
> + if (rc < 0)
> + goto err;
> + }
> +
> /* 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,
> @@ -372,11 +536,21 @@ static int __init acpi_pcc_probe(void)
> ((unsigned long) pcct_entry + pcct_entry->length);
> }
>
> - pcc_mbox_ctrl.num_chans = count;
> + pcc_mbox_ctrl.num_chans = sum;
>
> pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
>
> return 0;
> +
> +err:
> + kfree(pcc_doorbell_irq);
> +err_free_db_ack_vaddr:
> + kfree(pcc_doorbell_ack_vaddr);
> +err_free_db_vaddr:
> + kfree(pcc_doorbell_vaddr);
> +err_free_mbox:
> + kfree(pcc_mbox_channels);
> + return rc;
> }
>
> /**
> --
> 1.9.1
>
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