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Subject: Re: [PATCH v2 2/7] soc: qcom: Add AOSS QMP communication driver
To:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Andy Gross <andy.gross@linaro.org>,
        David Brown <david.brown@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>
Cc:     Russell King <linux@armlinux.org.uk>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20190106080915.4493-1-bjorn.andersson@linaro.org>
 <20190106080915.4493-3-bjorn.andersson@linaro.org>
From:   Arun Kumar Neelakantam <aneela@codeaurora.org>
Message-ID: <a162251c-bd84-356f-0f96-c733d775639d@codeaurora.org>
Date:   Thu, 10 Jan 2019 18:18:09 +0530
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On 1/6/2019 1:39 PM, Bjorn Andersson wrote:
> The AOSS QMP driver is used to communicate with the AOSS for certain
> side-channel requests, that are not enabled through the RPMh interface.
>
> The communication is a very simple synchronous mechanism of messages
> being written in message RAM and a doorbell in the AOSS is rung. As the
> AOSS has processed the message length is cleared and an interrupt is
> fired by the AOSS as acknowledgment.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
Reviewed-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
> Changes since v1:
> - Skip check in send for empty TX buffer
> - Don't follow WARN_ON() with dev_err()
> - Register platform_device rather than populate based on of-children
>
>   drivers/soc/qcom/Kconfig          |   9 +
>   drivers/soc/qcom/Makefile         |   1 +
>   drivers/soc/qcom/aoss-qmp.c       | 313 ++++++++++++++++++++++++++++++
>   include/linux/soc/qcom/aoss-qmp.h |  12 ++
>   4 files changed, 335 insertions(+)
>   create mode 100644 drivers/soc/qcom/aoss-qmp.c
>   create mode 100644 include/linux/soc/qcom/aoss-qmp.h
>
> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
> index a51458022d21..dda19471057f 100644
> --- a/drivers/soc/qcom/Kconfig
> +++ b/drivers/soc/qcom/Kconfig
> @@ -3,6 +3,15 @@
>   #
>   menu "Qualcomm SoC drivers"
>   
> +config QCOM_AOSS_QMP
> +	tristate "Qualcomm AOSS Messaging Driver"
> +	depends on ARCH_QCOM || COMPILE_TEST
> +	depends on MAILBOX
> +	help
> +	  This driver provides the means for communicating with the
> +	  micro-controller in the AOSS, using QMP, to control certain resource
> +	  that are not exposed through RPMh.
> +
>   config QCOM_COMMAND_DB
>   	bool "Qualcomm Command DB"
>   	depends on ARCH_QCOM || COMPILE_TEST
> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
> index 67cb85d0373c..d0d7fdc94d9a 100644
> --- a/drivers/soc/qcom/Makefile
> +++ b/drivers/soc/qcom/Makefile
> @@ -1,5 +1,6 @@
>   # SPDX-License-Identifier: GPL-2.0
>   CFLAGS_rpmh-rsc.o := -I$(src)
> +obj-$(CONFIG_QCOM_AOSS_QMP) +=	aoss-qmp.o
>   obj-$(CONFIG_QCOM_GENI_SE) +=	qcom-geni-se.o
>   obj-$(CONFIG_QCOM_COMMAND_DB) += cmd-db.o
>   obj-$(CONFIG_QCOM_GLINK_SSR) +=	glink_ssr.o
> diff --git a/drivers/soc/qcom/aoss-qmp.c b/drivers/soc/qcom/aoss-qmp.c
> new file mode 100644
> index 000000000000..de52703b96b6
> --- /dev/null
> +++ b/drivers/soc/qcom/aoss-qmp.c
> @@ -0,0 +1,313 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018, Linaro Ltd
> + */
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/soc/qcom/aoss-qmp.h>
> +
> +#define QMP_DESC_MAGIC			0x0
> +#define QMP_DESC_VERSION		0x4
> +#define QMP_DESC_FEATURES		0x8
> +
> +#define QMP_DESC_UCORE_LINK_STATE	0xc
> +#define QMP_DESC_UCORE_LINK_STATE_ACK	0x10
> +#define QMP_DESC_UCORE_CH_STATE		0x14
> +#define QMP_DESC_UCORE_CH_STATE_ACK	0x18
> +#define QMP_DESC_UCORE_MBOX_SIZE	0x1c
> +#define QMP_DESC_UCORE_MBOX_OFFSET	0x20
> +
> +#define QMP_DESC_MCORE_LINK_STATE	0x24
> +#define QMP_DESC_MCORE_LINK_STATE_ACK	0x28
> +#define QMP_DESC_MCORE_CH_STATE		0x2c
> +#define QMP_DESC_MCORE_CH_STATE_ACK	0x30
> +#define QMP_DESC_MCORE_MBOX_SIZE	0x34
> +#define QMP_DESC_MCORE_MBOX_OFFSET	0x38
> +
> +#define QMP_STATE_UP	0x0000ffff
> +#define QMP_STATE_DOWN	0xffff0000
> +
> +#define QMP_MAGIC	0x4d41494c
> +#define QMP_VERSION	1
> +
> +/**
> + * struct qmp - driver state for QMP implementation
> + * @msgram: iomem referencing the message RAM used for communication
> + * @dev: reference to QMP device
> + * @mbox_client: mailbox client used to ring the doorbell on transmit
> + * @mbox_chan: mailbox channel used to ring the doorbell on transmit
> + * @offset: offset within @msgram where messages should be written
> + * @size: maximum size of the messages to be transmitted
> + * @event: wait_queue for synchronization with the IRQ
> + * @tx_lock: provides syncrhonization between multiple callers of qmp_send()
> + * @pd_pdev: platform device for the power-domain child device
> + */
> +struct qmp {
> +	void __iomem *msgram;
> +	struct device *dev;
> +
> +	struct mbox_client mbox_client;
> +	struct mbox_chan *mbox_chan;
> +
> +	size_t offset;
> +	size_t size;
> +
> +	wait_queue_head_t event;
> +
> +	struct mutex tx_lock;
> +
> +	struct platform_device *pd_pdev;
> +};
> +
> +static void qmp_kick(struct qmp *qmp)
> +{
> +	mbox_send_message(qmp->mbox_chan, NULL);
> +	mbox_client_txdone(qmp->mbox_chan, 0);
> +}
> +
> +static bool qmp_magic_valid(struct qmp *qmp)
> +{
> +	return readl(qmp->msgram + QMP_DESC_MAGIC) == QMP_MAGIC;
> +}
> +
> +static bool qmp_link_acked(struct qmp *qmp)
> +{
> +	return readl(qmp->msgram + QMP_DESC_MCORE_LINK_STATE_ACK) == QMP_STATE_UP;
> +}
> +
> +static bool qmp_mcore_channel_acked(struct qmp *qmp)
> +{
> +	return readl(qmp->msgram + QMP_DESC_MCORE_CH_STATE_ACK) == QMP_STATE_UP;
> +}
> +
> +static bool qmp_ucore_channel_up(struct qmp *qmp)
> +{
> +	return readl(qmp->msgram + QMP_DESC_UCORE_CH_STATE) == QMP_STATE_UP;
> +}
> +
> +static int qmp_open(struct qmp *qmp)
> +{
> +	int ret;
> +	u32 val;
> +
> +	ret = wait_event_timeout(qmp->event, qmp_magic_valid(qmp), HZ);
> +	if (!ret) {
> +		dev_err(qmp->dev, "QMP magic doesn't match\n");
> +		return -ETIMEDOUT;
> +	}
> +
> +	val = readl(qmp->msgram + QMP_DESC_VERSION);
> +	if (val != QMP_VERSION) {
> +		dev_err(qmp->dev, "unsupported QMP version %d\n", val);
> +		return -EINVAL;
> +	}
> +
> +	qmp->offset = readl(qmp->msgram + QMP_DESC_MCORE_MBOX_OFFSET);
> +	qmp->size = readl(qmp->msgram + QMP_DESC_MCORE_MBOX_SIZE);
> +	if (!qmp->size) {
> +		dev_err(qmp->dev, "invalid mailbox size 0x%zx\n", qmp->size);
> +		return -EINVAL;
> +	}
> +
> +	/* Ack remote core's link state */
> +	val = readl(qmp->msgram + QMP_DESC_UCORE_LINK_STATE);
> +	writel(val, qmp->msgram + QMP_DESC_UCORE_LINK_STATE_ACK);
> +
> +	/* Set local core's link state to up */
> +	writel(QMP_STATE_UP, qmp->msgram + QMP_DESC_MCORE_LINK_STATE);
> +
> +	qmp_kick(qmp);
> +
> +	ret = wait_event_timeout(qmp->event, qmp_link_acked(qmp), HZ);
> +	if (!ret) {
> +		dev_err(qmp->dev, "ucore didn't ack link\n");
> +		goto timeout_close_link;
> +	}
> +
> +	writel(QMP_STATE_UP, qmp->msgram + QMP_DESC_MCORE_CH_STATE);
> +
> +	ret = wait_event_timeout(qmp->event, qmp_ucore_channel_up(qmp), HZ);
> +	if (!ret) {
> +		dev_err(qmp->dev, "ucore didn't open channel\n");
> +		goto timeout_close_channel;
> +	}
> +
> +	/* Ack remote core's channel state */
> +	val = readl(qmp->msgram + QMP_DESC_UCORE_CH_STATE);
> +	writel(val, qmp->msgram + QMP_DESC_UCORE_CH_STATE_ACK);
> +
> +	qmp_kick(qmp);
> +
> +	ret = wait_event_timeout(qmp->event, qmp_mcore_channel_acked(qmp), HZ);
> +	if (!ret) {
> +		dev_err(qmp->dev, "ucore didn't ack channel\n");
> +		goto timeout_close_channel;
> +	}
> +
> +	return 0;
> +
> +timeout_close_channel:
> +	writel(QMP_STATE_DOWN, qmp->msgram + QMP_DESC_MCORE_CH_STATE);
> +
> +timeout_close_link:
> +	writel(QMP_STATE_DOWN, qmp->msgram + QMP_DESC_MCORE_LINK_STATE);
> +	qmp_kick(qmp);
> +
> +	return -ETIMEDOUT;
> +}
> +
> +static void qmp_close(struct qmp *qmp)
> +{
> +	writel(QMP_STATE_DOWN, qmp->msgram + QMP_DESC_MCORE_CH_STATE);
> +	writel(QMP_STATE_DOWN, qmp->msgram + QMP_DESC_MCORE_LINK_STATE);
> +	qmp_kick(qmp);
> +}
> +
> +static irqreturn_t qmp_intr(int irq, void *data)
> +{
> +	struct qmp *qmp = data;
> +
> +	wake_up_interruptible_all(&qmp->event);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static bool qmp_message_empty(struct qmp *qmp)
> +{
> +	return readl(qmp->msgram + qmp->offset) == 0;
> +}
> +
> +/**
> + * qmp_send() - send a message to the AOSS
> + * @qmp: qmp context
> + * @data: message to be sent
> + * @len: length of the message
> + *
> + * Transmit @data to AOSS and wait for the AOSS to acknowledge the message.
> + * @len must be a multiple of 4 and not longer than the mailbox size. Access is
> + * synchronized by this implementation.
> + *
> + * Return: 0 on success, negative errno on failure
> + */
> +int qmp_send(struct qmp *qmp, const void *data, size_t len)
> +{
> +	int ret;
> +
> +	if (WARN_ON(len + sizeof(u32) > qmp->size))
> +		return -EINVAL;
> +
> +	if (WARN_ON(len % sizeof(u32)))
> +		return -EINVAL;
> +
> +	mutex_lock(&qmp->tx_lock);
> +
> +	/* The message RAM only implements 32-bit accesses */
> +	__iowrite32_copy(qmp->msgram + qmp->offset + sizeof(u32),
> +			 data, len / sizeof(u32));
> +	writel(len, qmp->msgram + qmp->offset);
> +	qmp_kick(qmp);
> +
> +	ret = wait_event_interruptible_timeout(qmp->event,
> +					       qmp_message_empty(qmp), HZ);
> +	if (!ret) {
> +		dev_err(qmp->dev, "ucore did not ack channel\n");
> +		ret = -ETIMEDOUT;
> +
> +		/* Clear message from buffer */
> +		writel(0, qmp->msgram + qmp->offset);
> +	} else {
> +		ret = 0;
> +	}
> +
> +	mutex_unlock(&qmp->tx_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(qmp_send);
> +
> +static int qmp_probe(struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	struct qmp *qmp;
> +	int irq;
> +	int ret;
> +
> +	qmp = devm_kzalloc(&pdev->dev, sizeof(*qmp), GFP_KERNEL);
> +	if (!qmp)
> +		return -ENOMEM;
> +
> +	qmp->dev = &pdev->dev;
> +	init_waitqueue_head(&qmp->event);
> +	mutex_init(&qmp->tx_lock);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	qmp->msgram = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(qmp->msgram))
> +		return PTR_ERR(qmp->msgram);
> +
> +	qmp->mbox_client.dev = &pdev->dev;
> +	qmp->mbox_client.knows_txdone = true;
> +	qmp->mbox_chan = mbox_request_channel(&qmp->mbox_client, 0);
> +	if (IS_ERR(qmp->mbox_chan)) {
> +		dev_err(&pdev->dev, "failed to acquire ipc mailbox\n");
> +		return PTR_ERR(qmp->mbox_chan);
> +	}
> +
> +	irq = platform_get_irq(pdev, 0);
> +	ret = devm_request_irq(&pdev->dev, irq, qmp_intr, IRQF_ONESHOT,
> +			       "aoss-qmp", qmp);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to request interrupt\n");
> +		return ret;
> +	}
> +
> +	ret = qmp_open(qmp);
> +	if (ret < 0)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, qmp);
> +
> +	if (of_property_read_bool(pdev->dev.of_node, "#power-domain-cells")) {
> +		qmp->pd_pdev = platform_device_register_data(&pdev->dev,
> +							     "aoss_qmp_pd",
> +							     PLATFORM_DEVID_NONE,
> +							     NULL, 0);
> +		if (IS_ERR(qmp->pd_pdev))
> +			dev_err(&pdev->dev, "failed to register AOSS PD\n");
> +	}
> +
> +	return 0;
> +}
> +
> +static int qmp_remove(struct platform_device *pdev)
> +{
> +	struct qmp *qmp = platform_get_drvdata(pdev);
> +
> +	platform_device_unregister(qmp->pd_pdev);
> +
> +	qmp_close(qmp);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id qmp_dt_match[] = {
> +	{ .compatible = "qcom,sdm845-aoss-qmp", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, qmp_dt_match);
> +
> +static struct platform_driver qmp_driver = {
> +	.driver = {
> +		.name		= "aoss_qmp",
> +		.of_match_table	= qmp_dt_match,
> +	},
> +	.probe = qmp_probe,
> +	.remove	= qmp_remove,
> +};
> +module_platform_driver(qmp_driver);
> +
> +MODULE_DESCRIPTION("Qualcomm AOSS QMP driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/soc/qcom/aoss-qmp.h b/include/linux/soc/qcom/aoss-qmp.h
> new file mode 100644
> index 000000000000..32ccaa091a9f
> --- /dev/null
> +++ b/include/linux/soc/qcom/aoss-qmp.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2018, Linaro Ltd
> + */
> +#ifndef __AOP_QMP_H__
> +#define __AOP_QMP_H__
> +
> +struct qmp;
> +
> +int qmp_send(struct qmp *qmp, const void *data, size_t len);
> +
> +#endif