mailbox: pcc: Support HW-Reduced Communication Subspace type 2

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.

Signed-off-by: Hoan Tran <hotran@apm.com>
Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 245 insertions, 71 deletions

diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
index 043828d541f7..08c87fadca8c 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;
 }
 
 /**