Date:   Tue, 06 Feb 2018 20:34:00 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Lina Iyer <ilina@...eaurora.org>
Cc:     tglx@...utronix.de, jason@...edaemon.net,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        rnayak@...eaurora.org, asathyak@...eaurora.org
Subject: Re: [PATCH v3 1/2] drivers: irqchip: pdc: Add PDC interrupt controller for QCOM SoCs

On Tue, 06 Feb 2018 18:09:04 +0000,
Lina Iyer wrote:
> 
> From : Archana Sathyakumar <asathyak@...eaurora.org>
> 
> The Power Domain Controller (PDC) on QTI SoCs like SDM845 houses an
> interrupt controller along with other domain control functions to handle
> interrupt related functions like handle falling edge or active low which
> are not detected at the GIC and handle wakeup interrupts.
> 
> The interrupt controller is on an always-on domain for the purpose of
> waking up the processor. Only a subset of the processor's interrupts are
> routed through the PDC to the GIC. The PDC powers on the processors'
> domain, when in low power mode and replays pending interrupts so the GIC
> may wake up the processor.
> 
> Signed-off-by: Archana Sathyakumar <asathyak@...eaurora.org>
> Signed-off-by: Lina Iyer <ilina@...eaurora.org>
> ---
>  drivers/irqchip/Kconfig    |   9 ++
>  drivers/irqchip/Makefile   |   1 +
>  drivers/irqchip/qcom-pdc.c | 302 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 312 insertions(+)
>  create mode 100644 drivers/irqchip/qcom-pdc.c
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index c70476b34a53..506c6aa7f0b4 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -343,4 +343,13 @@ config MESON_IRQ_GPIO
>         help
>           Support Meson SoC Family GPIO Interrupt Multiplexer
>  
> +config QCOM_PDC
> +	bool "QCOM PDC"
> +	depends on ARCH_QCOM
> +	select IRQ_DOMAIN
> +	select IRQ_DOMAIN_HIERARCHY
> +	help
> +	  Power Domain Controller driver to manage and configure wakeup
> +	  IRQs for Qualcomm Technologies Inc (QTI) mobile chips.
> +
>  endmenu
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index d2df34a54d38..280723d83916 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -84,3 +84,4 @@ obj-$(CONFIG_QCOM_IRQ_COMBINER)		+= qcom-irq-combiner.o
>  obj-$(CONFIG_IRQ_UNIPHIER_AIDET)	+= irq-uniphier-aidet.o
>  obj-$(CONFIG_ARCH_SYNQUACER)		+= irq-sni-exiu.o
>  obj-$(CONFIG_MESON_IRQ_GPIO)		+= irq-meson-gpio.o
> +obj-$(CONFIG_QCOM_PDC)			+= qcom-pdc.o
> diff --git a/drivers/irqchip/qcom-pdc.c b/drivers/irqchip/qcom-pdc.c
> new file mode 100644
> index 000000000000..88fa650f0653
> --- /dev/null
> +++ b/drivers/irqchip/qcom-pdc.c
> @@ -0,0 +1,302 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Coyright (c) 2017-2018, The Linux Foundation. All rights reserved. */
> +
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/irq.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqdomain.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +#define PDC_MAX_IRQS		126

>From v2: "Is that an absolute, architectural maximum? Or should it
come from the DT (being the sum of all ranges that are provided by
this PDC)?"

> +
> +#define CLEAR_INTR(reg, intr)	(reg & ~(1 << intr))
> +#define ENABLE_INTR(reg, intr)	(reg | (1 << intr))
> +
> +#define IRQ_ENABLE_BANK		0x10
> +#define IRQ_i_CFG		0x110
> +
> +struct pdc_pin_region {
> +	u32 pin_base;
> +	u32 parent_base;
> +	u32 cnt;
> +};
> +
> +static DEFINE_RAW_SPINLOCK(pdc_lock);
> +static void __iomem *pdc_base;
> +static struct pdc_pin_region *pdc_region;
> +static int pdc_region_cnt;
> +
> +static inline void pdc_reg_write(int reg, u32 i, u32 val)
> +{
> +	writel_relaxed(val, pdc_base + reg + i * sizeof(u32));
> +}
> +
> +static inline u32 pdc_reg_read(int reg, u32 i)
> +{
> +	return readl_relaxed(pdc_base + reg + i * sizeof(u32));
> +}
> +
> +static inline void pdc_enable_intr(struct irq_data *d, bool on)

You can loose the "inline" on these 3 function, I believe the compiler
will do a pretty good job specialising them.

> +{
> +	int pin_out = d->hwirq;
> +	u32 index, mask;
> +	u32 enable;
> +
> +	index = pin_out / 32;
> +	mask = pin_out % 32;
> +
> +	raw_spin_lock(&pdc_lock);
> +	enable = pdc_reg_read(IRQ_ENABLE_BANK, index);
> +	enable = on ? ENABLE_INTR(enable, mask) : CLEAR_INTR(enable, mask);
> +	pdc_reg_write(IRQ_ENABLE_BANK, index, enable);
> +	raw_spin_unlock(&pdc_lock);
> +}
> +
> +static void qcom_pdc_gic_mask(struct irq_data *d)
> +{
> +	pdc_enable_intr(d, false);
> +	irq_chip_mask_parent(d);
> +}
> +
> +static void qcom_pdc_gic_unmask(struct irq_data *d)
> +{
> +	pdc_enable_intr(d, true);
> +	irq_chip_unmask_parent(d);
> +}
> +
> +/*
> + * GIC does not handle falling edge or active low. To allow falling edge and
> + * active low interrupts to be handled at GIC, PDC has an inverter that inverts
> + * falling edge into a rising edge and active low into an active high.
> + * For the inverter to work, the polarity bit in the IRQ_CONFIG register has to
> + * set as per the table below.
> + * (polarity, falling edge, rising edge ) POLARITY
> + * 3'b0 00  Level sensitive active low    LOW
> + * 3'b0 01  Rising edge sensitive         NOT USED
> + * 3'b0 10  Falling edge sensitive        LOW
> + * 3'b0 11  Dual Edge sensitive           NOT USED
> + * 3'b1 00  Level senstive active High    HIGH

sensitive

> + * 3'b1 01  Falling Edge sensitive        NOT USED
> + * 3'b1 10  Rising edge sensitive         HIGH
> + * 3'b1 11  Dual Edge sensitive           HIGH
> + */
> +enum pdc_irq_config_bits {
> +	PDC_POLARITY_LOW	= 0,
> +	PDC_FALLING_EDGE	= 2,
> +	PDC_POLARITY_HIGH	= 4,
> +	PDC_RISING_EDGE		= 6,
> +	PDC_DUAL_EDGE		= 7,
> +};
> +
> +/**
> + * qcom_pdc_gic_set_type: Configure PDC for the interrupt
> + *
> + * @d: the interrupt data
> + * @type: the interrupt type
> + *
> + * If @type is edge triggered, forward that as Rising edge as PDC
> + * takes care of converting falling edge to rising edge signal
> + * If @type is level, then forward that as level high as PDC
> + * takes care of converting falling edge to rising edge signal
> + */
> +static int qcom_pdc_gic_set_type(struct irq_data *d, unsigned int type)
> +{
> +	int pin_out = d->hwirq;
> +	enum pdc_irq_config_bits pdc_type;
> +
> +	switch (type) {
> +	case IRQ_TYPE_EDGE_RISING:
> +		pdc_type = PDC_RISING_EDGE;
> +		type = IRQ_TYPE_EDGE_RISING;
> +		break;
> +	case IRQ_TYPE_EDGE_FALLING:
> +		pdc_type = PDC_FALLING_EDGE;
> +		type = IRQ_TYPE_EDGE_RISING;
> +		break;
> +	case IRQ_TYPE_EDGE_BOTH:
> +		pdc_type = PDC_DUAL_EDGE;
> +		break;
> +	case IRQ_TYPE_LEVEL_HIGH:
> +		pdc_type = PDC_POLARITY_HIGH;
> +		type = IRQ_TYPE_LEVEL_HIGH;
> +		break;
> +	case IRQ_TYPE_LEVEL_LOW:
> +		pdc_type = PDC_POLARITY_LOW;
> +		type = IRQ_TYPE_LEVEL_HIGH;
> +		break;
> +	default:
> +		WARN_ON(1);
> +		return -EINVAL;
> +	}
> +
> +	pdc_reg_write(IRQ_i_CFG, pin_out, pdc_type);
> +
> +	return irq_chip_set_type_parent(d, type);
> +}
> +
> +static struct irq_chip qcom_pdc_gic_chip = {

const?

> +	.name			= "pdc-gic",

Just call it "PDC".

> +	.irq_eoi		= irq_chip_eoi_parent,
> +	.irq_mask		= qcom_pdc_gic_mask,
> +	.irq_unmask		= qcom_pdc_gic_unmask,
> +	.irq_retrigger		= irq_chip_retrigger_hierarchy,
> +	.irq_set_type		= qcom_pdc_gic_set_type,
> +	.flags			= IRQCHIP_MASK_ON_SUSPEND |
> +				  IRQCHIP_SET_TYPE_MASKED |
> +				  IRQCHIP_SKIP_SET_WAKE,
> +	.irq_set_vcpu_affinity	= irq_chip_set_vcpu_affinity_parent,
> +#ifdef CONFIG_SMP
> +	.irq_set_affinity	= irq_chip_set_affinity_parent,
> +#endif

Is this supposed to work on any architecture other than arm64? If not,
then you can loose the CONFIG_SMP, as there is no !SMP config on arm64.

> +};
> +
> +static irq_hw_number_t get_parent_hwirq(int pin)
> +{
> +	int i;
> +	struct pdc_pin_region *region;
> +
> +	for (i = 0; i < pdc_region_cnt; i++) {
> +		region = &pdc_region[i];
> +		if (pin >= region->pin_base &&
> +		   pin < region->pin_base + region->cnt)
> +			return (region->parent_base + pin - region->pin_base);
> +	}
> +
> +	WARN_ON(1);
> +	return pin;

Do not return a valid value in case of error. Please return an error
value that you will check in the caller. Otherwise you're feeding the
GIC with a SPI number that is actually a PDC pin number. That is not
going to have any positive effect.

> +}
> +
> +static int qcom_pdc_translate(struct irq_domain *d,
> +	struct irq_fwspec *fwspec, unsigned long *hwirq, unsigned int *type)
> +{
> +	if (is_of_node(fwspec->fwnode)) {
> +		if (fwspec->param_count != 2)
> +			return -EINVAL;
> +
> +		*hwirq = fwspec->param[0];
> +		*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int qcom_pdc_alloc(struct irq_domain *domain,
> +			unsigned int virq, unsigned int nr_irqs, void *data)
> +{
> +	struct irq_fwspec *fwspec = data;
> +	struct irq_fwspec parent_fwspec;
> +	irq_hw_number_t hwirq, parent_hwirq;
> +	unsigned int type;
> +	int ret;
> +
> +	ret = qcom_pdc_translate(domain, fwspec, &hwirq, &type);
> +	if (ret)
> +		return -EINVAL;
> +
> +	parent_hwirq = get_parent_hwirq(hwirq);
> +	ret  = irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
> +					    &qcom_pdc_gic_chip,
> +					    (void *)parent_hwirq);

Nothing else in this driver should be concerned with the parent hwirq,
so NULL should be an appropriate value for chip_data.

> +	if (ret)
> +		return ret;
> +
> +	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_pdc_ops = {
> +	.translate	= qcom_pdc_translate,
> +	.alloc		= qcom_pdc_alloc,
> +	.free		= irq_domain_free_irqs_common,
> +};
> +
> +static int pdc_setup_pin_mapping(struct device_node *np)
> +{
> +	u32 *region = NULL;
> +	int ret, n;
> +
> +	n = of_property_count_elems_of_size(np, "qcom,pdc-ranges", sizeof(u32));
> +	if (!n || n % 3)
> +		return -EINVAL;
> +
> +	region = kcalloc(n, sizeof(*region), GFP_KERNEL);
> +	if (!region)
> +		return -ENOMEM;
> +
> +	ret = of_property_read_u32_array(np, "qcom,pdc-ranges", region, n);
> +	if (ret) {
> +		kfree(region);
> +		return -EINVAL;
> +	}
> +
> +	pdc_region = (struct pdc_pin_region *)region;

Oh please... Don't resort to that kind of hack. Next thing you know,
someone will add a u8 field to that structure and you'll spend the
following 2 hours trying to understand why it all went so wrong.
Allocate a bounce buffer if you want, copy fields one by one, I don't
care. Just don't do that. :-(

> +	pdc_region_cnt = n / 3;
> +
> +	return 0;
> +}
> +
> +int qcom_pdc_init(struct device_node *node, struct device_node *parent)

static.

> +{
> +	struct irq_domain *parent_domain, *pdc_domain;
> +	int ret;
> +
> +	pdc_base = of_iomap(node, 0);
> +	if (!pdc_base) {
> +		pr_err("%s: unable to map PDC registers\n", node->full_name);
> +		return -ENXIO;
> +	}
> +
> +	parent_domain = irq_find_host(parent);
> +	if (!parent_domain) {
> +		pr_err("%s: unable to obtain PDC parent domain\n",
> +		      node->full_name);

Use %pOF instead of %s and node->full_name in all occurrences in this
function  (see commit ce4fecf1fe15).

> +		ret = -ENXIO;
> +		goto failure;
> +	}
> +
> +	ret = pdc_setup_pin_mapping(node);
> +	if (ret) {
> +		pr_err("%s: failed to init PDC pin mapping\n", node->full_name);
> +		goto failure;
> +	}
> +
> +	pdc_domain = irq_domain_create_hierarchy(parent_domain, 0, PDC_MAX_IRQS,
> +						of_fwnode_handle(node),
> +						&qcom_pdc_ops, NULL);
> +	if (!pdc_domain) {
> +		pr_err("%s: GIC domain add failed\n", node->full_name);
> +		ret = -ENOMEM;
> +		goto failure;
> +	}
> +
> +	return 0;
> +
> +failure:
> +	kfree(pdc_region);
> +	iounmap(pdc_base);
> +	return ret;
> +}
> +
> +IRQCHIP_DECLARE(pdc_sdm845, "qcom,sdm845-pdc", qcom_pdc_init);
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.

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