ACPI 5.0+ spec defines a generic mode of communication between the OS and a platform such as the BMC. This medium (PCC) is typically used by CPPC (ACPI CPU Performance management), RAS (ACPI reliability protocol) and MPST (ACPI Memory power states).

This patch adds PCC support as a Mailbox Controller.

Signed-off-by: Ashwin Chaugule ashwin.chaugule@linaro.org --- drivers/mailbox/Kconfig | 12 ++ drivers/mailbox/Makefile | 2 + drivers/mailbox/mailbox.c | 4 - drivers/mailbox/pcc.c | 297 +++++++++++++++++++++++++++++++++++++ include/linux/mailbox_controller.h | 4 + 5 files changed, 315 insertions(+), 4 deletions(-) create mode 100644 drivers/mailbox/pcc.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig index c8b5c13..e08cc83 100644 --- a/drivers/mailbox/Kconfig +++ b/drivers/mailbox/Kconfig @@ -50,4 +50,16 @@ config OMAP_MBOX_KFIFO_SIZE Specify the default size of mailbox's kfifo buffers (bytes). This can also be changed at runtime (via the mbox_kfifo_size module parameter). + +config PCC + bool "Platform Communication Channel Driver" + depends on ACPI + help + ACPI 5.0+ spec defines a generic mode of communication + between the OS and a platform such as the BMC. This medium + (PCC) is typically used by CPPC (ACPI CPU Performance management), + RAS (ACPI reliability protocol) and MPST (ACPI Memory power + states). Select this driver if your platform implements the + PCC clients mentioned above. + endif diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile index 2fa343a..0b09d6f 100644 --- a/drivers/mailbox/Makefile +++ b/drivers/mailbox/Makefile @@ -9,3 +9,5 @@ obj-$(CONFIG_OMAP1_MBOX) += mailbox_omap1.o mailbox_omap1-objs := mailbox-omap1.o obj-$(CONFIG_OMAP2PLUS_MBOX) += mailbox_omap2.o mailbox_omap2-objs := mailbox-omap2.o + +obj-$(CONFIG_PCC) += pcc.o diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c index 63ecc17..e07cfb0 100644 --- a/drivers/mailbox/mailbox.c +++ b/drivers/mailbox/mailbox.c @@ -21,10 +21,6 @@ #include <linux/mailbox_client.h> #include <linux/mailbox_controller.h>

-#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */ -#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */ -#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */ - static LIST_HEAD(mbox_cons); static DEFINE_MUTEX(con_mutex);

diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c new file mode 100644 index 0000000..f910c96 --- /dev/null +++ b/drivers/mailbox/pcc.c @@ -0,0 +1,297 @@ +/* + * Copyright (C) 2014 Linaro Ltd. + * Author: Ashwin Chaugule ashwin.chaugule@linaro.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#include <linux/acpi.h> +#include <linux/io.h> +#include <linux/uaccess.h> +#include <linux/init.h> +#include <linux/cpufreq.h> +#include <linux/delay.h> +#include <linux/ioctl.h> +#include <linux/vmalloc.h> +#include <linux/module.h> +#include <linux/mailbox_controller.h> +#include <linux/mailbox_client.h> +#include <linux/platform_device.h> + +#include <acpi/actbl.h> + +#define MAX_PCC_SUBSPACES 256 +#define PCCS_SS_SIG_MAGIC 0x50434300 +#define PCC_CMD_COMPLETE 0x1 + +static struct mbox_chan pcc_mbox_chan[MAX_PCC_SUBSPACES]; +static struct mbox_controller pcc_mbox_ctrl = {}; + +struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, + int index) +{ + struct device *dev = pcc_mbox_ctrl.dev; + struct mbox_chan *chan; + unsigned long flags; + + /* + * Each PCC Subspace is a Mailbox Channel. + * The PCC Clients get their PCC Subspace ID + * from their own tables and pass it here. + * This returns a pointer to the PCC subspace + * for the Client to operate on. + */ + chan = &pcc_mbox_chan[index]; + + if (!chan || chan->cl || !try_module_get(dev->driver->owner)) { + dev_err(dev, "%s: PCC mailbox not free\n", __func__); + return ERR_PTR(-EBUSY); + } + + spin_lock_irqsave(&chan->lock, flags); + chan->msg_free = 0; + chan->msg_count = 0; + chan->active_req = NULL; + chan->cl = cl; + init_completion(&chan->tx_complete); + + if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) + chan->txdone_method |= TXDONE_BY_ACK; + + spin_unlock_irqrestore(&chan->lock, flags); + + return chan; +} +EXPORT_SYMBOL_GPL(pcc_mbox_request_channel); + +void pcc_mbox_free_channel(struct mbox_chan *chan) +{ + unsigned long flags; + + if (!chan || !chan->cl) + 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; + + module_put(chan->mbox->dev->driver->owner); + spin_unlock_irqrestore(&chan->lock, flags); +} +EXPORT_SYMBOL_GPL(pcc_mbox_free_channel); + +static bool pcc_tx_done(struct mbox_chan *chan) +{ + struct acpi_pcct_subspace *pcct_ss = chan->con_priv; + struct acpi_pcct_shared_memory *generic_comm_base = + (struct acpi_pcct_shared_memory *) pcct_ss->base_address; + u16 cmd_delay = pcct_ss->min_turnaround_time; + + /* Wait for Platform to consume. */ + while (!(ioread16(&generic_comm_base->status) & PCC_CMD_COMPLETE)) + udelay(cmd_delay); + + return true; +} + +static int get_subspace_id(struct mbox_chan *chan) +{ + unsigned int i; + + for (i = 0; i < pcc_mbox_ctrl.num_chans; i++) { + if (chan == &pcc_mbox_chan[i]) + return i; + } + + return -ENOENT; +} + +/* Channel lock is already held by mbox controller code. */ +static int pcc_send_data(struct mbox_chan *chan, void *data) +{ + struct acpi_pcct_subspace *pcct_ss = chan->con_priv; + struct acpi_pcct_shared_memory *generic_comm_base = + (struct acpi_pcct_shared_memory *) pcct_ss->base_address; + struct acpi_generic_address doorbell; + u64 doorbell_preserve; + u64 doorbell_val; + u64 doorbell_write; + u16 cmd = 0; + u16 ss_idx = -1; + int ret = 0; + + /* Get PCC CMD */ + ret = kstrtou16((char*)data, 0, &cmd); + if (ret < 0) { + pr_err("Err while converting PCC CMD to u16: %d\n", ret); + goto out_err; + } + + ss_idx = get_subspace_id(chan); + + if (ss_idx < 0) { + pr_err("Invalid Subspace ID from PCC client\n"); + ret = ss_idx; + goto out_err; + } + + doorbell = pcct_ss->doorbell_register; + doorbell_preserve = pcct_ss->preserve_mask; + doorbell_write = pcct_ss->write_mask; + + /* Write to the shared comm region. */ + iowrite16(cmd, &generic_comm_base->command); + + /* Write Subspace MAGIC value so platform can identify destination. */ + iowrite32((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature); + + /* Flip CMD COMPLETE bit */ + iowrite16(0, &generic_comm_base->status); + + /* Sync notification from OSPM to Platform. */ + acpi_read(&doorbell_val, &doorbell); + acpi_write((doorbell_val & doorbell_preserve) | doorbell_write, + &doorbell); + +out_err: + return ret; +} + +static struct mbox_chan_ops pcc_chan_ops = { + .send_data = pcc_send_data, + .last_tx_done = pcc_tx_done, +}; + +static int parse_pcc_subspace(struct acpi_subtable_header *header, + const unsigned long end) +{ + struct acpi_pcct_subspace *pcct_ss; + + if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) { + pcct_ss = (struct acpi_pcct_subspace *) header; + + if (pcct_ss->header.type != ACPI_PCCT_TYPE_GENERIC_SUBSPACE) { + pr_err("Incorrect PCC Subspace type detected\n"); + return -EINVAL; + } + + /* New mbox channel entry for each PCC subspace detected. */ + pcc_mbox_chan[pcc_mbox_ctrl.num_chans].con_priv = pcct_ss; + pcc_mbox_ctrl.num_chans++; + + } else { + pr_err("No more space for PCC subspaces.\n"); + return -ENOSPC; + } + + return 0; +} + +/* + * Create a virtual device to back the PCCT, so + * that the generic Mailbox framework can do its + * ref counting. + */ +struct platform_device pcc_pdev = { + .name = "PCCT", +}; + +static int __init acpi_pcc_probe(void) +{ + acpi_status status = AE_OK; + acpi_size pcct_tbl_header_size; + struct acpi_table_pcct *pcct_tbl; + int ret; + + /* Search for PCCT */ + status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0, + (struct acpi_table_header **)&pcct_tbl, + &pcct_tbl_header_size); + + if (ACPI_SUCCESS(status) && !pcct_tbl) { + pr_warn("PCCT header not found.\n"); + status = AE_NOT_FOUND; + goto out_err; + } + + status = acpi_table_parse_entries(ACPI_SIG_PCCT, + sizeof(struct acpi_table_pcct), + ACPI_PCCT_TYPE_GENERIC_SUBSPACE, + parse_pcc_subspace, MAX_PCC_SUBSPACES); + + if (ACPI_SUCCESS(status)) + pr_err("Error parsing PCC subspaces from PCCT\n"); + + pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans); + + pcc_mbox_ctrl.chans = pcc_mbox_chan; + pcc_mbox_ctrl.ops = &pcc_chan_ops; + pcc_mbox_ctrl.txdone_poll = true; + pcc_mbox_ctrl.txpoll_period = 1; + + ret = platform_device_register(&pcc_pdev); + + if (ret) { + pr_err ("Err registering PCC platform device\n"); + return -ENODEV; + } + +out_err: + return ACPI_SUCCESS(status) ? 1 : 0; +} + +static int pcc_mbox_probe(struct platform_device *pdev) +{ + int ret = 0; + + pcc_mbox_ctrl.dev = &pdev->dev; + + pr_info("Registering PCC driver as Mailbox controller\n"); + ret = mbox_controller_register(&pcc_mbox_ctrl); + + if (ret) { + pr_err("Err registering PCC as Mailbox controller: %d\n", ret); + ret = -ENODEV; + } + + return ret; +} + +struct platform_driver pcc_mbox_driver = { + .probe = pcc_mbox_probe, + .driver = { + .name = "PCCT", + .owner = THIS_MODULE, + }, +}; + +static int __init pcc_init(void) +{ + int ret; + + if (acpi_disabled) + return -ENODEV; + + /* Check if PCC support is available. */ + ret = acpi_pcc_probe(); + + if (ret) { + pr_debug("PCC probe failed.\n"); + return -EINVAL; + } + + return platform_driver_register(&pcc_mbox_driver); +} + +device_initcall(pcc_init); diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h index 9ee195b..956cc06 100644 --- a/include/linux/mailbox_controller.h +++ b/include/linux/mailbox_controller.h @@ -15,6 +15,10 @@

struct mbox_chan;

+#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */ +#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */ +#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */ + /** * struct mbox_chan_ops - methods to control mailbox channels * @send_data: The API asks the MBOX controller driver, in atomic

Hi,

From: linux-acpi-owner@vger.kernel.org [mailto:linux-acpi-owner@vger.kernel.org] On Behalf Of Ashwin Chaugule Sent: Thursday, September 04, 2014 6:19 AM

ACPI 5.0+ spec defines a generic mode of communication between the OS and a platform such as the BMC. This medium (PCC) is typically used by CPPC (ACPI CPU Performance management), RAS (ACPI reliability protocol) and MPST (ACPI Memory power states).

This patch adds PCC support as a Mailbox Controller.

Signed-off-by: Ashwin Chaugule ashwin.chaugule@linaro.org

drivers/mailbox/Kconfig | 12 ++ drivers/mailbox/Makefile | 2 + drivers/mailbox/mailbox.c | 4 - drivers/mailbox/pcc.c | 297 +++++++++++++++++++++++++++++++++++++ include/linux/mailbox_controller.h | 4 + 5 files changed, 315 insertions(+), 4 deletions(-) create mode 100644 drivers/mailbox/pcc.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig index c8b5c13..e08cc83 100644 --- a/drivers/mailbox/Kconfig +++ b/drivers/mailbox/Kconfig @@ -50,4 +50,16 @@ config OMAP_MBOX_KFIFO_SIZE Specify the default size of mailbox's kfifo buffers (bytes). This can also be changed at runtime (via the mbox_kfifo_size module parameter).

+config PCC

• bool "Platform Communication Channel Driver"
• depends on ACPI
• help

• ACPI 5.0+ spec defines a generic mode of communication
  

• between the OS and a platform such as the BMC. This medium
  

• (PCC) is typically used by CPPC (ACPI CPU Performance management),
  

• RAS (ACPI reliability protocol) and MPST (ACPI Memory power
  

• states). Select this driver if your platform implements the
  

• PCC clients mentioned above.
  

endif diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile index 2fa343a..0b09d6f 100644 --- a/drivers/mailbox/Makefile +++ b/drivers/mailbox/Makefile @@ -9,3 +9,5 @@ obj-$(CONFIG_OMAP1_MBOX) += mailbox_omap1.o mailbox_omap1-objs := mailbox-omap1.o obj-$(CONFIG_OMAP2PLUS_MBOX) += mailbox_omap2.o mailbox_omap2-objs := mailbox-omap2.o

+obj-$(CONFIG_PCC) += pcc.o diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c index 63ecc17..e07cfb0 100644 --- a/drivers/mailbox/mailbox.c +++ b/drivers/mailbox/mailbox.c @@ -21,10 +21,6 @@ #include <linux/mailbox_client.h> #include <linux/mailbox_controller.h>

-#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */ -#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */ -#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */

static LIST_HEAD(mbox_cons); static DEFINE_MUTEX(con_mutex);

diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c new file mode 100644 index 0000000..f910c96 --- /dev/null +++ b/drivers/mailbox/pcc.c @@ -0,0 +1,297 @@ +/*

• • Copyright (C) 2014 Linaro Ltd.
• • Author: Ashwin Chaugule ashwin.chaugule@linaro.org
• • This program is free software; you can redistribute it and/or modify
• • it under the terms of the GNU General Public License as published by
• • the Free Software Foundation; either version 2 of the License, or
• • (at your option) any later version.
• • This program is distributed in the hope that it will be useful,
• • but WITHOUT ANY WARRANTY; without even the implied warranty of
• • MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
• • GNU General Public License for more details.
• */

+#include <linux/acpi.h> +#include <linux/io.h> +#include <linux/uaccess.h> +#include <linux/init.h> +#include <linux/cpufreq.h> +#include <linux/delay.h> +#include <linux/ioctl.h> +#include <linux/vmalloc.h> +#include <linux/module.h> +#include <linux/mailbox_controller.h> +#include <linux/mailbox_client.h> +#include <linux/platform_device.h>

+#include <acpi/actbl.h>

Please do not include this directly, it is already included by <linux/acpi.h> even when CONFIG is N. See <linux/acpi.h> -> <acpi/acpi.h> -> <acpi/actbl.h>

Thanks and best regards -Lv

+#define MAX_PCC_SUBSPACES 256 +#define PCCS_SS_SIG_MAGIC 0x50434300 +#define PCC_CMD_COMPLETE 0x1

+static struct mbox_chan pcc_mbox_chan[MAX_PCC_SUBSPACES]; +static struct mbox_controller pcc_mbox_ctrl = {};

+struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,

• int index)
  

+{

• struct device *dev = pcc_mbox_ctrl.dev;
• struct mbox_chan *chan;
• unsigned long flags;
• /*

• * Each PCC Subspace is a Mailbox Channel.
  

• * The PCC Clients get their PCC Subspace ID
  

• * from their own tables and pass it here.
  

• * This returns a pointer to the PCC subspace
  

• * for the Client to operate on.
  

• */
  

• chan = &pcc_mbox_chan[index];
• if (!chan || chan->cl || !try_module_get(dev->driver->owner)) {

• dev_err(dev, "%s: PCC mailbox not free\n", __func__);
  

• return ERR_PTR(-EBUSY);
  

• }
• spin_lock_irqsave(&chan->lock, flags);
• chan->msg_free = 0;
• chan->msg_count = 0;
• chan->active_req = NULL;
• chan->cl = cl;
• init_completion(&chan->tx_complete);
• if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)

• chan->txdone_method |= TXDONE_BY_ACK;
  

• spin_unlock_irqrestore(&chan->lock, flags);
• return chan;

+} +EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);

+void pcc_mbox_free_channel(struct mbox_chan *chan) +{

• unsigned long flags;
• if (!chan || !chan->cl)

• 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;
  

• module_put(chan->mbox->dev->driver->owner);
• spin_unlock_irqrestore(&chan->lock, flags);

+} +EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);

+static bool pcc_tx_done(struct mbox_chan *chan) +{

• struct acpi_pcct_subspace *pcct_ss = chan->con_priv;
• struct acpi_pcct_shared_memory *generic_comm_base =

• (struct acpi_pcct_shared_memory *) pcct_ss->base_address;
  

• u16 cmd_delay = pcct_ss->min_turnaround_time;
• /* Wait for Platform to consume. */
• while (!(ioread16(&generic_comm_base->status) & PCC_CMD_COMPLETE))

• udelay(cmd_delay);
  

• return true;

+}

+static int get_subspace_id(struct mbox_chan *chan) +{

• unsigned int i;
• for (i = 0; i < pcc_mbox_ctrl.num_chans; i++) {

• if (chan == &pcc_mbox_chan[i])
  

• 	return i;
  

• }
• return -ENOENT;

+}

+/* Channel lock is already held by mbox controller code. */ +static int pcc_send_data(struct mbox_chan *chan, void *data) +{

• struct acpi_pcct_subspace *pcct_ss = chan->con_priv;
• struct acpi_pcct_shared_memory *generic_comm_base =

• (struct acpi_pcct_shared_memory *) pcct_ss->base_address;
  

• struct acpi_generic_address doorbell;
• u64 doorbell_preserve;
• u64 doorbell_val;
• u64 doorbell_write;
• u16 cmd = 0;
• u16 ss_idx = -1;
• int ret = 0;
• /* Get PCC CMD */
• ret = kstrtou16((char*)data, 0, &cmd);
• if (ret < 0) {

• pr_err("Err while converting PCC CMD to u16: %d\n", ret);
  

• goto out_err;
  

• }
• ss_idx = get_subspace_id(chan);
• if (ss_idx < 0) {

• pr_err("Invalid Subspace ID from PCC client\n");
  

• ret = ss_idx;
  

• goto out_err;
  

• }
• doorbell = pcct_ss->doorbell_register;
• doorbell_preserve = pcct_ss->preserve_mask;
• doorbell_write = pcct_ss->write_mask;
• /* Write to the shared comm region. */
• iowrite16(cmd, &generic_comm_base->command);
• /* Write Subspace MAGIC value so platform can identify destination. */
• iowrite32((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
• /* Flip CMD COMPLETE bit */
• iowrite16(0, &generic_comm_base->status);
• /* Sync notification from OSPM to Platform. */
• acpi_read(&doorbell_val, &doorbell);
• acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,

• 	&doorbell);
  

+out_err:

• return ret;

+}

+static struct mbox_chan_ops pcc_chan_ops = {

• .send_data = pcc_send_data,
• .last_tx_done = pcc_tx_done,

+};

+static int parse_pcc_subspace(struct acpi_subtable_header *header,

• const unsigned long end)
  

+{

• struct acpi_pcct_subspace *pcct_ss;
• if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {

• pcct_ss = (struct acpi_pcct_subspace *) header;
  

• if (pcct_ss->header.type != ACPI_PCCT_TYPE_GENERIC_SUBSPACE) {
  

• 	pr_err("Incorrect PCC Subspace type detected\n");
  

• 	return -EINVAL;
  

• }
  

• /* New mbox channel entry for each PCC subspace detected. */
  

• pcc_mbox_chan[pcc_mbox_ctrl.num_chans].con_priv = pcct_ss;
  

• pcc_mbox_ctrl.num_chans++;
  

• } else {

• pr_err("No more space for PCC subspaces.\n");
  

• return -ENOSPC;
  

• }
• return 0;

+}

+/*

• • Create a virtual device to back the PCCT, so
• • that the generic Mailbox framework can do its
• • ref counting.
• */

+struct platform_device pcc_pdev = {

• .name = "PCCT",

+};

+static int __init acpi_pcc_probe(void) +{

• acpi_status status = AE_OK;
• acpi_size pcct_tbl_header_size;
• struct acpi_table_pcct *pcct_tbl;
• int ret;
• /* Search for PCCT */
• status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,

• 	(struct acpi_table_header **)&pcct_tbl,
  

• 	&pcct_tbl_header_size);
  

• if (ACPI_SUCCESS(status) && !pcct_tbl) {

• pr_warn("PCCT header not found.\n");
  

• status = AE_NOT_FOUND;
  

• goto out_err;
  

• }
• status = acpi_table_parse_entries(ACPI_SIG_PCCT,

• 	sizeof(struct acpi_table_pcct),
  

• 	ACPI_PCCT_TYPE_GENERIC_SUBSPACE,
  

• 	parse_pcc_subspace, MAX_PCC_SUBSPACES);
  

• if (ACPI_SUCCESS(status))

• pr_err("Error parsing PCC subspaces from PCCT\n");
  

• pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
• pcc_mbox_ctrl.chans = pcc_mbox_chan;
• pcc_mbox_ctrl.ops = &pcc_chan_ops;
• pcc_mbox_ctrl.txdone_poll = true;
• pcc_mbox_ctrl.txpoll_period = 1;
• ret = platform_device_register(&pcc_pdev);
• if (ret) {

• pr_err ("Err registering PCC platform device\n");
  

• return -ENODEV;
  

• }

+out_err:

• return ACPI_SUCCESS(status) ? 1 : 0;

+}

+static int pcc_mbox_probe(struct platform_device *pdev) +{

• int ret = 0;
• pcc_mbox_ctrl.dev = &pdev->dev;
• pr_info("Registering PCC driver as Mailbox controller\n");
• ret = mbox_controller_register(&pcc_mbox_ctrl);
• if (ret) {

• pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
  

• ret = -ENODEV;
  

• }
• return ret;

+}

+struct platform_driver pcc_mbox_driver = {

• .probe = pcc_mbox_probe,
• .driver = {

• .name = "PCCT",
  

• .owner = THIS_MODULE,
  

• },

+};

+static int __init pcc_init(void) +{

• int ret;
• if (acpi_disabled)

• return -ENODEV;
  

• /* Check if PCC support is available. */
• ret = acpi_pcc_probe();
• if (ret) {

• pr_debug("PCC probe failed.\n");
  

• return -EINVAL;
  

• }
• return platform_driver_register(&pcc_mbox_driver);

+}

+device_initcall(pcc_init); diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h index 9ee195b..956cc06 100644 --- a/include/linux/mailbox_controller.h +++ b/include/linux/mailbox_controller.h @@ -15,6 +15,10 @@

struct mbox_chan;

+#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */ +#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */ +#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */

/**

• struct mbox_chan_ops - methods to control mailbox channels
• @send_data: The API asks the MBOX controller driver, in atomic

-- 1.9.1

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On Wednesday 03 September 2014 18:19:19 Ashwin Chaugule wrote:

ACPI 5.0+ spec defines a generic mode of communication between the OS and a platform such as the BMC. This medium (PCC) is typically used by CPPC (ACPI CPU Performance management), RAS (ACPI reliability protocol) and MPST (ACPI Memory power states).

Ok, the interaction with the mailbox subsystem looks much nicer now!

Some comments on the actual driver:

+struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,

• int index)
  

+{

• struct device *dev = pcc_mbox_ctrl.dev;
• struct mbox_chan *chan;
• unsigned long flags;
• /*

• * Each PCC Subspace is a Mailbox Channel.
  

• * The PCC Clients get their PCC Subspace ID
  

• * from their own tables and pass it here.
  

• * This returns a pointer to the PCC subspace
  

• * for the Client to operate on.
  

• */
  

• chan = &pcc_mbox_chan[index];
• if (!chan || chan->cl || !try_module_get(dev->driver->owner)) {

• dev_err(dev, "%s: PCC mailbox not free\n", __func__);
  

• return ERR_PTR(-EBUSY);
  

• }

The try_module_get is now pointless, since dev->driver->owner is the current module.

+static int get_subspace_id(struct mbox_chan *chan) +{

• unsigned int i;
• for (i = 0; i < pcc_mbox_ctrl.num_chans; i++) {

• if (chan == &pcc_mbox_chan[i])
  

• 	return i;
  

• }
• return -ENOENT;

+}

Isn't this the same as this?

int id = chan - pcc_mbox_chan; if (id < 0 || id > pcc_mbox_ctrl.num_chans return -ENOENT; return id;

+/* Channel lock is already held by mbox controller code. */ +static int pcc_send_data(struct mbox_chan *chan, void *data) +{

• struct acpi_pcct_subspace *pcct_ss = chan->con_priv;
• struct acpi_pcct_shared_memory *generic_comm_base =

• (struct acpi_pcct_shared_memory *) pcct_ss->base_address;
  

• struct acpi_generic_address doorbell;
• u64 doorbell_preserve;
• u64 doorbell_val;
• u64 doorbell_write;
• u16 cmd = 0;
• u16 ss_idx = -1;
• int ret = 0;
• /* Get PCC CMD */
• ret = kstrtou16((char*)data, 0, &cmd);

What is this supposed to do? Why would a client pass data as a string? Just make it a u16 pointer and force the client to do the conversion so you have a proper format.

Mailbox drivers should generally have a fixed-format mailbox data pointer.

• /* Write to the shared comm region. */
• iowrite16(cmd, &generic_comm_base->command);
• /* Write Subspace MAGIC value so platform can identify destination. */
• iowrite32((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
• /* Flip CMD COMPLETE bit */
• iowrite16(0, &generic_comm_base->status);

using writel_relaxed/writew_relaxed should be more efficient here.

• • Create a virtual device to back the PCCT, so
• • that the generic Mailbox framework can do its
• • ref counting.
• */

+struct platform_device pcc_pdev = {

• .name = "PCCT",

+};

Don't declare platform devices statically in C code, just use platform_create_bundle() here to create the device dynamically and bind it to the driver. That will also simplify the driver initalization.

diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h index 9ee195b..956cc06 100644 --- a/include/linux/mailbox_controller.h +++ b/include/linux/mailbox_controller.h @@ -15,6 +15,10 @@ struct mbox_chan; +#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */ +#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */ +#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */

/**

• struct mbox_chan_ops - methods to control mailbox channels
• @send_data: The API asks the MBOX controller driver, in atomic

I don't think we want these in a global header file. Better put them in a local header file in drivers/mailbox/.

Arnd

Hi Arnd,

On 4 September 2014 04:56, Arnd Bergmann arnd@arndb.de wrote:

On Wednesday 03 September 2014 18:19:19 Ashwin Chaugule wrote:

...

ACPI 5.0+ spec defines a generic mode of communication between the OS and a platform such as the BMC. This medium (PCC) is typically used by CPPC (ACPI CPU Performance management), RAS (ACPI reliability protocol) and MPST (ACPI Memory power states).

Ok, the interaction with the mailbox subsystem looks much nicer now!

Cool. Thanks for the help!

Some comments on the actual driver:

...

+struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,

•         int index)
  

+{

• struct device *dev = pcc_mbox_ctrl.dev;
  

• struct mbox_chan *chan;
  

• unsigned long flags;
  

• /*
  

•  * Each PCC Subspace is a Mailbox Channel.
  

•  * The PCC Clients get their PCC Subspace ID
  

•  * from their own tables and pass it here.
  

•  * This returns a pointer to the PCC subspace
  

•  * for the Client to operate on.
  

•  */
  

• chan = &pcc_mbox_chan[index];
  

• if (!chan || chan->cl || !try_module_get(dev->driver->owner)) {
  

•         dev_err(dev, "%s: PCC mailbox not free\n", __func__);
  

•         return ERR_PTR(-EBUSY);
  

• }
  

The try_module_get is now pointless, since dev->driver->owner is the current module.

:) Yea, it occurred to me as well, but I wasn't too sure.

...

+static int get_subspace_id(struct mbox_chan *chan) +{

• unsigned int i;
  

• for (i = 0; i < pcc_mbox_ctrl.num_chans; i++) {
  

•         if (chan == &pcc_mbox_chan[i])
  

•                 return i;
  

• }
  

• return -ENOENT;
  

+}

Isn't this the same as this?

    int id = chan - pcc_mbox_chan;
    if (id < 0 || id > pcc_mbox_ctrl.num_chans
            return -ENOENT;
    return id;

Seems better.

...

+/* Channel lock is already held by mbox controller code. */ +static int pcc_send_data(struct mbox_chan *chan, void *data) +{

• struct acpi_pcct_subspace *pcct_ss = chan->con_priv;
  

• struct acpi_pcct_shared_memory *generic_comm_base =
  

•         (struct acpi_pcct_shared_memory *) pcct_ss->base_address;
  

• struct acpi_generic_address doorbell;
  

• u64 doorbell_preserve;
  

• u64 doorbell_val;
  

• u64 doorbell_write;
  

• u16 cmd = 0;
  

• u16 ss_idx = -1;
  

• int ret = 0;
  

• /* Get PCC CMD */
  

• ret = kstrtou16((char*)data, 0, &cmd);
  

What is this supposed to do? Why would a client pass data as a string? Just make it a u16 pointer and force the client to do the conversion so you have a proper format.

Mailbox drivers should generally have a fixed-format mailbox data pointer.

Ok.

...

• /* Write to the shared comm region. */
  

• iowrite16(cmd, &generic_comm_base->command);
  

• /* Write Subspace MAGIC value so platform can identify destination. */
  

• iowrite32((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
  

• /* Flip CMD COMPLETE bit */
  

• iowrite16(0, &generic_comm_base->status);
  

using writel_relaxed/writew_relaxed should be more efficient here.

Ok.

...

• • Create a virtual device to back the PCCT, so
• • that the generic Mailbox framework can do its
• • ref counting.
• */

+struct platform_device pcc_pdev = {

• .name = "PCCT",
  

+};

Don't declare platform devices statically in C code, just use platform_create_bundle() here to create the device dynamically and bind it to the driver. That will also simplify the driver initalization.

Nice. Didn't know about this.

...

diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h index 9ee195b..956cc06 100644 --- a/include/linux/mailbox_controller.h +++ b/include/linux/mailbox_controller.h @@ -15,6 +15,10 @@

struct mbox_chan;

+#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */ +#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */ +#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */

/**

• struct mbox_chan_ops - methods to control mailbox channels
• @send_data: The API asks the MBOX controller driver, in atomic

I don't think we want these in a global header file. Better put them in a local header file in drivers/mailbox/.

Ok.

Thanks, Ashwin