Date:   Wed, 16 Feb 2022 15:48:42 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Shawn Guo <shawn.guo@...aro.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Maulik Shah <quic_mkshah@...cinc.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/3] irqchip: Add Qualcomm MPM controller driver

On 2022-02-16 13:28, Shawn Guo wrote:
> Qualcomm SoCs based on the RPM architecture have a MSM Power Manager 
> (MPM)
> in always-on domain. In addition to managing resources during sleep, 
> the
> hardware also has an interrupt controller that monitors the interrupts
> when the system is asleep, wakes up the APSS when one of these 
> interrupts
> occur and replays it to GIC after it becomes operational.
> 
> It adds an irqchip driver for this interrupt controller, and here are
> some notes about it.
> 
> - For given SoC, a fixed number of MPM pins are supported, e.g. 96 pins
>   on QCM2290.  Each of these MPM pins can be either a MPM_GIC pin or
>   a MPM_GPIO pin. The mapping between MPM_GIC pin and GIC interrupt
>   is defined by SoC, as well as the mapping between MPM_GPIO pin and
>   GPIO number.  The former mapping is retrieved from device tree, while
>   the latter is defined in TLMM pinctrl driver.
> 
> - Different from vendor driver that handles MPM_GIC and MPM_GPIO pin
>   with separate irq_domain (and irq_chip), it handles both with a 
> single
>   irq_domain, and distinguishes them by checking parent IRQ, since only
>   MPM_GIC pin has a parent GIC SPI number.

I don't think we need this paragraph. Out of tree code is pretty much
irrelevant.

> 
> - When SoC gets awake from sleep mode, the driver will receive an
>   interrupt from RPM, so that it can replay interrupt for particular
>   polarity.
> 
> Signed-off-by: Shawn Guo <shawn.guo@...aro.org>
> ---
>  drivers/irqchip/Kconfig    |   8 +
>  drivers/irqchip/Makefile   |   1 +
>  drivers/irqchip/qcom-mpm.c | 440 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 449 insertions(+)
>  create mode 100644 drivers/irqchip/qcom-mpm.c
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 7038957f4a77..680d2fcf2686 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -430,6 +430,14 @@ config QCOM_PDC
>  	  Power Domain Controller driver to manage and configure wakeup
>  	  IRQs for Qualcomm Technologies Inc (QTI) mobile chips.
> 
> +config QCOM_MPM
> +	tristate "QCOM MPM"
> +	depends on ARCH_QCOM
> +	select IRQ_DOMAIN_HIERARCHY
> +	help
> +	  MSM Power Manager driver to manage and configure wakeup
> +	  IRQs for Qualcomm Technologies Inc (QTI) mobile chips.
> +
>  config CSKY_MPINTC
>  	bool
>  	depends on CSKY
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index c1f611cbfbf8..0e2e10467e28 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -94,6 +94,7 @@ obj-$(CONFIG_MESON_IRQ_GPIO)		+= irq-meson-gpio.o
>  obj-$(CONFIG_GOLDFISH_PIC) 		+= irq-goldfish-pic.o
>  obj-$(CONFIG_NDS32)			+= irq-ativic32.o
>  obj-$(CONFIG_QCOM_PDC)			+= qcom-pdc.o
> +obj-$(CONFIG_QCOM_MPM)			+= qcom-mpm.o
>  obj-$(CONFIG_CSKY_MPINTC)		+= irq-csky-mpintc.o
>  obj-$(CONFIG_CSKY_APB_INTC)		+= irq-csky-apb-intc.o
>  obj-$(CONFIG_RISCV_INTC)		+= irq-riscv-intc.o
> diff --git a/drivers/irqchip/qcom-mpm.c b/drivers/irqchip/qcom-mpm.c
> new file mode 100644
> index 000000000000..06c2ed14635f
> --- /dev/null
> +++ b/drivers/irqchip/qcom-mpm.c
> @@ -0,0 +1,440 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2021, Linaro Limited
> + * Copyright (c) 2010-2020, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/cpu_pm.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqchip/arm-gic-v3.h>
> +#include <linux/irqdomain.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/soc/qcom/irq.h>
> +#include <linux/spinlock.h>
> +
> +/*
> + * This is the driver for Qualcomm MPM (MSM Power Manager) interrupt
> controller,
> + * which is commonly found on Qualcomm SoCs built on the RPM 
> architecture.
> + * Sitting in always-on domain, MPM monitors the wakeup interrupts 
> when SoC is
> + * asleep, and wakes up the AP when one of those interrupts occurs.
> This driver
> + * doesn't directly access physical MPM registers though.  Instead, 
> the access
> + * is bridged via a piece of internal memory (SRAM) that is accessible 
> to both
> + * AP and RPM.  This piece of memory is called 'vMPM' in the driver.
> + *
> + * When SoC is awake, the vMPM is owned by AP and the register setup 
> by this
> + * driver all happens on vMPM.  When AP is about to get power 
> collapsed, the
> + * driver sends a mailbox notification to RPM, which will take over 
> the vMPM
> + * ownership and dump vMPM into physical MPM registers.  On wakeup, AP 
> is woken
> + * up by a MPM pin/interrupt, and RPM will copy STATUS registers into 
> vMPM.
> + * Then AP start owning vMPM again.
> + *
> + * vMPM register map:
> + *
> + *    31                              0
> + *    +--------------------------------+
> + *    |            TIMER0              | 0x00
> + *    +--------------------------------+
> + *    |            TIMER1              | 0x04
> + *    +--------------------------------+
> + *    |            ENABLE0             | 0x08
> + *    +--------------------------------+
> + *    |              ...               | ...
> + *    +--------------------------------+
> + *    |            ENABLEn             |
> + *    +--------------------------------+
> + *    |          FALLING_EDGE0         |
> + *    +--------------------------------+
> + *    |              ...               |
> + *    +--------------------------------+
> + *    |            STATUSn             |
> + *    +--------------------------------+
> + *
> + *    n = DIV_ROUND_UP(pin_cnt, 32)
> + *
> + */
> +
> +#define MPM_REG_ENABLE		0
> +#define MPM_REG_FALLING_EDGE	1
> +#define MPM_REG_RISING_EDGE	2
> +#define MPM_REG_POLARITY	3
> +#define MPM_REG_STATUS		4
> +
> +#define MPM_NO_PARENT_IRQ	~0UL
> +
> +/* MPM pin map to GIC hwirq */
> +struct mpm_gic_map {
> +	int pin;
> +	irq_hw_number_t hwirq;
> +};
> +
> +struct qcom_mpm_priv {
> +	void __iomem *base;
> +	raw_spinlock_t lock;
> +	struct mbox_client mbox_client;
> +	struct mbox_chan *mbox_chan;
> +	struct mpm_gic_map *maps;
> +	unsigned int map_cnt;
> +	unsigned int reg_stride;
> +	struct irq_domain *domain;
> +	struct notifier_block pm_nb;
> +};
> +
> +static u32 qcom_mpm_read(struct qcom_mpm_priv *priv, unsigned int reg,
> +			 unsigned int index)
> +{
> +	unsigned int offset = (reg * priv->reg_stride + index + 2) * 4;
> +
> +	return readl_relaxed(priv->base + offset);
> +}
> +
> +static void qcom_mpm_write(struct qcom_mpm_priv *priv, unsigned int 
> reg,
> +			   unsigned int index, u32 val)
> +{
> +	unsigned int offset = (reg * priv->reg_stride + index + 2) * 4;
> +
> +	writel_relaxed(val, priv->base + offset);
> +
> +	/* Ensure the write is completed */
> +	wmb();
> +}
> +
> +static void qcom_mpm_enable_irq(struct irq_data *d, bool en)
> +{
> +	struct qcom_mpm_priv *priv = d->chip_data;
> +	int pin = d->hwirq;
> +	unsigned int index = pin / 32;
> +	unsigned int shift = pin % 32;
> +	unsigned long flags;
> +	u32 val;
> +
> +	raw_spin_lock_irqsave(&priv->lock, flags);
> +
> +	val = qcom_mpm_read(priv, MPM_REG_ENABLE, index);
> +	if (en)
> +		val |= BIT(shift);
> +	else
> +		val &= ~BIT(shift);
> +	qcom_mpm_write(priv, MPM_REG_ENABLE, index, val);
> +
> +	raw_spin_unlock_irqrestore(&priv->lock, flags);
> +}
> +
> +static void qcom_mpm_mask(struct irq_data *d)
> +{
> +	qcom_mpm_enable_irq(d, false);
> +
> +	if (d->parent_data)
> +		irq_chip_mask_parent(d);
> +}
> +
> +static void qcom_mpm_unmask(struct irq_data *d)
> +{
> +	qcom_mpm_enable_irq(d, true);
> +
> +	if (d->parent_data)
> +		irq_chip_unmask_parent(d);
> +}
> +
> +static void mpm_set_type(struct qcom_mpm_priv *priv, bool set,
> unsigned int reg,
> +			 unsigned int index, unsigned int shift)
> +{
> +	unsigned long flags;
> +	u32 val;
> +
> +	raw_spin_lock_irqsave(&priv->lock, flags);
> +
> +	val = qcom_mpm_read(priv, reg, index);
> +	if (set)
> +		val |= BIT(shift);
> +	else
> +		val &= ~BIT(shift);
> +	qcom_mpm_write(priv, reg, index, val);
> +
> +	raw_spin_unlock_irqrestore(&priv->lock, flags);
> +}
> +
> +static int qcom_mpm_set_type(struct irq_data *d, unsigned int type)
> +{
> +	struct qcom_mpm_priv *priv = d->chip_data;
> +	int pin = d->hwirq;
> +	unsigned int index = pin / 32;
> +	unsigned int shift = pin % 32;
> +
> +	switch (type & IRQ_TYPE_SENSE_MASK) {
> +	case IRQ_TYPE_EDGE_RISING:
> +		mpm_set_type(priv, !!(type & IRQ_TYPE_EDGE_RISING),
> +			     MPM_REG_RISING_EDGE, index, shift);
> +		break;
> +	case IRQ_TYPE_EDGE_FALLING:
> +		mpm_set_type(priv, !!(type & IRQ_TYPE_EDGE_FALLING),
> +			     MPM_REG_FALLING_EDGE, index, shift);
> +		break;
> +	case IRQ_TYPE_LEVEL_HIGH:
> +		mpm_set_type(priv, !!(type & IRQ_TYPE_LEVEL_HIGH),
> +			     MPM_REG_POLARITY, index, shift);
> +		break;
> +	}
> +
> +	if (!d->parent_data)
> +		return 0;
> +
> +	if (type & IRQ_TYPE_EDGE_BOTH)
> +		type = IRQ_TYPE_EDGE_RISING;
> +
> +	if (type & IRQ_TYPE_LEVEL_MASK)
> +		type = IRQ_TYPE_LEVEL_HIGH;
> +
> +	return irq_chip_set_type_parent(d, type);
> +}
> +
> +static struct irq_chip qcom_mpm_chip = {
> +	.name			= "mpm",
> +	.irq_eoi		= irq_chip_eoi_parent,
> +	.irq_mask		= qcom_mpm_mask,
> +	.irq_unmask		= qcom_mpm_unmask,
> +	.irq_retrigger		= irq_chip_retrigger_hierarchy,
> +	.irq_set_type		= qcom_mpm_set_type,
> +	.irq_set_affinity	= irq_chip_set_affinity_parent,
> +	.flags			= IRQCHIP_MASK_ON_SUSPEND |
> +				  IRQCHIP_SKIP_SET_WAKE,
> +};
> +
> +static irq_hw_number_t get_parent_hwirq(struct qcom_mpm_priv *priv, 
> int pin)
> +{
> +	const struct mpm_gic_map *maps = priv->maps;
> +	int i;
> +
> +	for (i = 0; i < priv->map_cnt; i++) {
> +		if (maps[i].pin == pin)
> +			return maps[i].hwirq;
> +	}
> +
> +	return MPM_NO_PARENT_IRQ;

I'd rather you change this helper to return a pointer to the mapping 
data,
and NULL on failure. This will avoid inventing magic values which may
or may not clash with an interrupt number in the future.

> +}
> +
> +static int qcom_mpm_alloc(struct irq_domain *domain, unsigned int 
> virq,
> +			  unsigned int nr_irqs, void *data)
> +{
> +	struct qcom_mpm_priv *priv = domain->host_data;
> +	struct irq_fwspec *fwspec = data;
> +	struct irq_fwspec parent_fwspec;
> +	irq_hw_number_t parent_hwirq;

Isn't this the pin number? If so, I'd rather you call it that.

> +	irq_hw_number_t hwirq;
> +	unsigned int type;
> +	int  ret;
> +
> +	ret = irq_domain_translate_twocell(domain, fwspec, &hwirq, &type);
> +	if (ret)
> +		return ret;
> +
> +	ret = irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
> +					    &qcom_mpm_chip, priv);
> +	if (ret)
> +		return ret;
> +
> +	parent_hwirq = get_parent_hwirq(priv, hwirq);
> +	if (parent_hwirq == MPM_NO_PARENT_IRQ)
> +		return irq_domain_disconnect_hierarchy(domain->parent, virq);
> +
> +	if (type & IRQ_TYPE_EDGE_BOTH)
> +		type = IRQ_TYPE_EDGE_RISING;
> +
> +	if (type & IRQ_TYPE_LEVEL_MASK)
> +		type = IRQ_TYPE_LEVEL_HIGH;
> +
> +	parent_fwspec.fwnode = domain->parent->fwnode;
> +	parent_fwspec.param_count = 3;
> +	parent_fwspec.param[0] = 0;
> +	parent_fwspec.param[1] = parent_hwirq;
> +	parent_fwspec.param[2] = type;
> +
> +	return irq_domain_alloc_irqs_parent(domain, virq, nr_irqs,
> +					    &parent_fwspec);
> +}
> +
> +static const struct irq_domain_ops qcom_mpm_ops = {
> +	.alloc		= qcom_mpm_alloc,
> +	.free		= irq_domain_free_irqs_common,
> +	.translate	= irq_domain_translate_twocell,
> +};
> +
> +/* Triggered by RPM when system resumes from deep sleep */
> +static irqreturn_t qcom_mpm_handler(int irq, void *dev_id)
> +{
> +	struct qcom_mpm_priv *priv = dev_id;
> +	unsigned long enable, pending;
> +	int i, j;
> +
> +	for (i = 0; i < priv->reg_stride; i++) {
> +		enable = qcom_mpm_read(priv, MPM_REG_ENABLE, i);
> +		pending = qcom_mpm_read(priv, MPM_REG_STATUS, i);
> +		pending &= enable;
> 

Is it safe to run all this without any form of locking? From what I can
tell, other CPUs could enable and disable interrupts in parallel to 
this.

> +		for_each_set_bit(j, &pending, 32) {
> +			unsigned int pin = 32 * i + j;
> +			struct irq_desc *desc = irq_resolve_mapping(priv->domain, pin);
> +			struct irq_data *d = &desc->irq_data;
> +
> +			if (!irqd_is_level_type(d))
> +				irq_set_irqchip_state(d->irq,
> +						IRQCHIP_STATE_PENDING, true);
> +
> +		}
> +	}
> +
> +	return IRQ_HANDLED;

This can obviously be reached without any interrupt being actually 
handled.

> +}
> +
> +static int qcom_mpm_enter_sleep(struct qcom_mpm_priv *priv)
> +{
> +	int i, ret;
> +
> +	for (i = 0; i < priv->reg_stride; i++)
> +		qcom_mpm_write(priv, MPM_REG_STATUS, i, 0);
> +
> +	/* Notify RPM to write vMPM into HW */
> +	ret = mbox_send_message(priv->mbox_chan, NULL);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int qcom_mpm_cpu_pm_callback(struct notifier_block *nb,
> +				    unsigned long action, void *data)
> +{
> +	struct qcom_mpm_priv *priv = container_of(nb, struct qcom_mpm_priv,
> +						  pm_nb);
> +	int ret = NOTIFY_OK;
> +
> +	switch (action) {
> +	case CPU_CLUSTER_PM_ENTER:
> +		if (qcom_mpm_enter_sleep(priv))
> +			ret = NOTIFY_BAD;
> +		break;
> +	default:
> +		return NOTIFY_DONE;

ret = NOTIFY_DONE; ?

> +	}
> +
> +	return ret;
> +}
> +
> +static int qcom_mpm_init(struct device_node *np, struct device_node 
> *parent)
> +{
> +	struct platform_device *pdev = of_find_device_by_node(np);
> +	struct device *dev = &pdev->dev;
> +	struct irq_domain *parent_domain;
> +	struct qcom_mpm_priv *priv;
> +	unsigned int pin_cnt;
> +	int i, irq;
> +	int ret;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	ret = of_property_read_u32(np, "qcom,mpm-pin-count", &pin_cnt);
> +	if (ret) {
> +		dev_err(dev, "failed to read qcom,mpm-pin-count: %d\n", ret);
> +		return ret;
> +	}
> +
> +	priv->reg_stride = DIV_ROUND_UP(pin_cnt, 32);
> +
> +	ret = of_property_count_u32_elems(np, "qcom,mpm-pin-map");
> +	if (ret < 0) {
> +		dev_err(dev, "failed to read qcom,mpm-pin-map: %d\n", ret);
> +		return ret;
> +	}
> +
> +	if (ret % 2) {
> +		dev_err(dev, "invalid qcom,mpm-pin-map\n");
> +		return -EINVAL;
> +	}
> +
> +	priv->map_cnt = ret / 2;
> +	priv->maps = devm_kcalloc(dev, priv->map_cnt, sizeof(*priv->maps),
> +				  GFP_KERNEL);
> +	if (!priv->maps)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < priv->map_cnt; i++) {
> +		of_property_read_u32_index(np, "qcom,mpm-pin-map", i * 2,
> +					   &priv->maps[i].pin);
> +		of_property_read_u32_index(np, "qcom,mpm-pin-map", i * 2 + 1,
> +					   (u32 *) &priv->maps[i].hwirq);
> +	}
> +
> +	raw_spin_lock_init(&priv->lock);
> +
> +	priv->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (!priv->base)
> +		return PTR_ERR(priv->base);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return irq;
> +
> +	priv->mbox_client.dev = dev;
> +	priv->mbox_chan = mbox_request_channel(&priv->mbox_client, 0);
> +	if (IS_ERR(priv->mbox_chan)) {
> +		ret = PTR_ERR(priv->mbox_chan);
> +		dev_err(dev, "failed to acquire IPC channel: %d\n", ret);
> +		return ret;
> +	}
> +
> +	parent_domain = irq_find_host(parent);
> +	if (!parent_domain) {
> +		dev_err(dev, "failed to find MPM parent domain\n");
> +		ret = -ENXIO;
> +		goto free_mbox;
> +	}
> +
> +	priv->domain = irq_domain_create_hierarchy(parent_domain,
> +				IRQ_DOMAIN_FLAG_QCOM_MPM_WAKEUP, pin_cnt,
> +				of_node_to_fwnode(np), &qcom_mpm_ops, priv);
> +	if (!priv->domain) {
> +		dev_err(dev, "failed to create MPM domain\n");
> +		ret = -ENOMEM;
> +		goto free_mbox;
> +	}
> +
> +	irq_domain_update_bus_token(priv->domain, DOMAIN_BUS_WAKEUP);
> +
> +	ret = devm_request_irq(dev, irq, qcom_mpm_handler,
> +			       IRQF_TRIGGER_RISING | IRQF_NO_SUSPEND,

Can you just get the trigger type as exposed by the device tree?
In general, you shouldn't have to specify it at all.

> +			       "qcom_mpm", priv);
> +	if (ret) {
> +		dev_err(dev, "failed to request irq: %d\n", ret);
> +		goto remove_domain;
> +	}
> +
> +	priv->pm_nb.notifier_call = qcom_mpm_cpu_pm_callback;
> +	cpu_pm_register_notifier(&priv->pm_nb);
> +
> +	dev_set_drvdata(dev, priv);

What is the use of this? I don't see anything retrieving it...

> +
> +	return 0;
> +
> +remove_domain:
> +	irq_domain_remove(priv->domain);
> +free_mbox:
> +	mbox_free_channel(priv->mbox_chan);
> +	return ret;
> +}
> +
> +IRQCHIP_PLATFORM_DRIVER_BEGIN(qcom_mpm)
> +IRQCHIP_MATCH("qcom,mpm", qcom_mpm_init)
> +IRQCHIP_PLATFORM_DRIVER_END(qcom_mpm)
> +MODULE_DESCRIPTION("Qualcomm Technologies, Inc. MSM Power Manager");
> +MODULE_LICENSE("GPL v2");

Other than that, this is starting to look OK. You 'only' need to
work out how to to get a last-man-standing notification in a way
that is manageable.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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