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

Hoan Tran
2016-05-06T18:39:11Z

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 = {};

-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;
+
+ chan = pcc_chan->chan;
+ 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;
+
+ 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_chan->pcc_doorbell_ack_vaddr,
+ &doorbell_ack_val,
+ doorbell_ack->bit_width);
+ if (ret)
+ return IRQ_NONE;
+
+ 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 IRQ_NONE;
+ }
+
+ return IRQ_HANDLED;
}

/**
@@ -107,7 +260,8 @@ static struct mbox_chan *get_pcc_channel(int id)
struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
int subspace_id)
{
- struct device *dev = pcc_mbox_ctrl.dev;
+ struct device *dev = pcc_mbox_ctx.mbox_ctrl.dev;
+ struct pcc_mbox_chan *pcc_chan;
struct mbox_chan *chan;
unsigned long flags;

@@ -118,8 +272,13 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
* This returns a pointer to the PCC subspace
* for the Client to operate on.
*/
- chan = get_pcc_channel(subspace_id);
+ pcc_chan = get_pcc_channel(subspace_id);
+ if (IS_ERR(pcc_chan)) {
+ dev_err(dev, "PCC Channel not found for idx: %d\n", subspace_id);
+ return ERR_PTR(-EBUSY);
+ }

+ chan = pcc_chan->chan;
if (IS_ERR(chan) || chan->cl) {
dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
return ERR_PTR(-EBUSY);
@@ -135,6 +294,18 @@ 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_chan->irq > 0) {
+ int rc;
+
+ rc = devm_request_irq(dev, pcc_chan->irq, pcc_mbox_irq, 0,
+ MBOX_IRQ_NAME, pcc_chan);
+ if (unlikely(rc)) {
+ dev_err(dev, "failed to register PCC interrupt %d\n",
+ pcc_chan->irq);
+ chan = ERR_PTR(rc);
+ }
+ }
+
spin_unlock_irqrestore(&chan->lock, flags);

return chan;
@@ -149,7 +320,9 @@ EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
*/
void pcc_mbox_free_channel(struct mbox_chan *chan)
{
+ struct pcc_mbox_chan *pcc_chan;
unsigned long flags;
+ u32 id;

if (!chan || !chan->cl)
return;
@@ -160,69 +333,19 @@ void pcc_mbox_free_channel(struct mbox_chan *chan)
if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
chan->txdone_method = TXDONE_BY_POLL;

+ id = chan - pcc_mbox_ctx.chans;
+ pcc_chan = get_pcc_channel(id);
+ if (IS_ERR(pcc_chan)) {
+ pr_debug("PCC Channel not found for idx: %d\n", id);
+ } else {
+ if (pcc_chan->irq > 0)
+ devm_free_irq(chan->mbox->dev, pcc_chan->irq, 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
@@ -240,36 +363,44 @@ static int pcc_send_data(struct mbox_chan *chan, void *data)
{
struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
struct acpi_generic_address *doorbell;
+ struct pcc_mbox_chan *pcc_chan;
u64 doorbell_preserve;
u64 doorbell_val;
u64 doorbell_write;
- u32 id = chan - pcc_mbox_channels;
- int ret = 0;
+ u32 id = chan - pcc_mbox_ctx.chans;
+ int ret;

- if (id >= pcc_mbox_ctrl.num_chans) {
+ if (id >= pcc_mbox_ctx.mbox_ctrl.num_chans) {
pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
return -ENOENT;
}

+ pcc_chan = get_pcc_channel(id);
+ if (IS_ERR(pcc_chan)) {
+ pr_debug("PCC Channel not found for idx: %d\n", id);
+ return -EBUSY;
+ }
+
doorbell = &pcct_ss->doorbell_register;
doorbell_preserve = pcct_ss->preserve_mask;
doorbell_write = pcct_ss->write_mask;

/* Sync notification from OS to Platform. */
- if (pcc_doorbell_vaddr[id]) {
- ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
- doorbell->bit_width);
+ if (pcc_chan->pcc_doorbell_vaddr) {
+ ret = read_register(pcc_chan->pcc_doorbell_vaddr, &doorbell_val,
+ doorbell->bit_width);
if (ret)
return ret;
- ret = write_register(pcc_doorbell_vaddr[id],
- (doorbell_val & doorbell_preserve) | doorbell_write,
- doorbell->bit_width);
+ ret = write_register(pcc_chan->pcc_doorbell_vaddr,
+ (doorbell_val & doorbell_preserve)
+ | doorbell_write,
+ doorbell->bit_width);
} else {
ret = acpi_read(&doorbell_val, doorbell);
if (ret)
return ret;
ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
- doorbell);
+ doorbell);
}
return ret;
}
@@ -293,11 +424,13 @@ static int parse_pcc_subspace(struct acpi_subtable_header *header,
{
struct acpi_pcct_hw_reduced *pcct_ss;

- if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
+ if (pcc_mbox_ctx.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 +440,43 @@ 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.
+ * @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) {
+ struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
+
+ mbox_chans->pcc_doorbell_ack_vaddr = acpi_os_ioremap(
+ pcct2_ss->doorbell_ack_register.address,
+ pcct2_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 +486,8 @@ 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 */
@@ -334,22 +505,28 @@ static int __init acpi_pcc_probe(void)
ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
parse_pcc_subspace, MAX_PCC_SUBSPACES);

+ 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) {
pr_err("Error parsing PCC subspaces from PCCT\n");
return -EINVAL;
}

- pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
- count, GFP_KERNEL);
+ pcc_mbox_ctx.chans = kzalloc(sizeof(struct mbox_chan) *
+ count, GFP_KERNEL);

- if (!pcc_mbox_channels) {
+ if (!pcc_mbox_ctx.chans) {
pr_err("Could not allocate space for PCC mbox channels\n");
return -ENOMEM;
}

- pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
- if (!pcc_doorbell_vaddr) {
- kfree(pcc_mbox_channels);
+ pcc_mbox_ctx.mbox_chans = kzalloc(sizeof(struct pcc_mbox_chan) *
+ count, GFP_KERNEL);
+ if (!pcc_mbox_ctx.mbox_chans) {
+ pr_err("Could not allocate space for PCC mbox channel data\n");
return -ENOMEM;
}

@@ -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;
+ }

/* 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);

if (ret) {
pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
--
1.9.1

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