Re: [Linaro-acpi] [PATCH v6 1/2] Mailbox: Add support for Platform Communication Channel

Hi,

From: linux-acpi-owner@vger.kernel.org [mailto:linux-acpi-owner@vger.kernel.org] On Behalf Of Ashwin Chaugule Sent: Friday, September 05, 2014 2:49 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/mailbox.h | 16 +++ drivers/mailbox/pcc.c | 279 ++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 310 insertions(+), 3 deletions(-) create mode 100644 drivers/mailbox/mailbox.h 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..9d9366a 100644 --- a/drivers/mailbox/mailbox.c +++ b/drivers/mailbox/mailbox.c @@ -21,9 +21,7 @@ #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 */ +#include "mailbox.h"

static LIST_HEAD(mbox_cons); static DEFINE_MUTEX(con_mutex); diff --git a/drivers/mailbox/mailbox.h b/drivers/mailbox/mailbox.h new file mode 100644 index 0000000..5a15a25 --- /dev/null +++ b/drivers/mailbox/mailbox.h @@ -0,0 +1,16 @@ +/*

• • This program is free software; you can redistribute it and/or modify
• • it under the terms of the GNU General Public License version 2 as
• • published by the Free Software Foundation.
• */

+#ifndef __MAILBOX_H +#define __MAILBOX_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 */

+#endif /* __MAILBOX_H */

diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c new file mode 100644 index 0000000..7831a01 --- /dev/null +++ b/drivers/mailbox/pcc.c @@ -0,0 +1,279 @@ +/*

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

+#include "mailbox.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) {

• 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)

The tab should be a space here?

• 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;
  

• 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;

Should these parameters be acquired with chan-lock held? Is that possible to change them during runtime?

• /* Wait for Platform to consume. */
• while (!(readw_relaxed(&generic_comm_base->status) & PCC_CMD_COMPLETE))

• udelay(cmd_delay);
  

• return true;

+}

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

• 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;
  

Ditto.

• struct acpi_generic_address doorbell;
• u64 doorbell_preserve;
• u64 doorbell_val;
• u64 doorbell_write;
• u16 cmd = *(u16 *) data;
• u16 ss_idx = -1;
• int ret = 0;
• ss_idx = get_subspace_id(chan);
• if (ss_idx < 0) {

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

• ret = -EINVAL;
  

• 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. */
• writew(cmd, &generic_comm_base->command);
• /* Write Subspace MAGIC value so platform can identify destination. */
• writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
• /* Flip CMD COMPLETE bit */
• writew(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;

+}

+static int __init acpi_pcc_probe(void) +{

• acpi_status status = AE_OK;
• acpi_size pcct_tbl_header_size;
• struct acpi_table_pcct *pcct_tbl;
• /* 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;

+out_err:

• return ACPI_SUCCESS(status) ? 1 : 0;

Should the return value of 1 here be -EINVAL?

Thanks and best regards -Lv

+}

+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;
• struct platform_device *pcc_pdev;
• if (acpi_disabled)

• return -ENODEV;
  

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

• pr_debug("ACPI PCC probe failed.\n");
  

• return -EINVAL;
  

• }
• pcc_pdev = platform_create_bundle(&pcc_mbox_driver,

• 	pcc_mbox_probe, NULL, 0, NULL, 0);
  

• if (!pcc_pdev) {

• pr_err("Err creating PCC platform bundle\n");
  

• return -ENODEV;
  

• }
• return 0;

+}

+device_initcall(pcc_init);

1.9.1

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