RE: [PATCH V3 2/2] drivers/irqchip: add NXP INTMUX interrupt multiplexer support

[Joakim Zhang]

> -----Original Message-----
> From: Lokesh Vutla <lokeshvutla@xxxxxx>
> Sent: 2019å12æ20æ 19:45
> To: Joakim Zhang <qiangqing.zhang@xxxxxxx>; maz@xxxxxxxxxx;
> tglx@xxxxxxxxxxxxx; jason@xxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx;
> mark.rutland@xxxxxxx; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx
> Cc: Andy Duan <fugang.duan@xxxxxxx>; S.j. Wang
> <shengjiu.wang@xxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; dl-linux-imx
> <linux-imx@xxxxxxx>; kernel@xxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH V3 2/2] drivers/irqchip: add NXP INTMUX interrupt
> multiplexer support
> 
> 
> 
> On 20/12/19 1:07 PM, Joakim Zhang wrote:
> > The Interrupt Multiplexer (INTMUX) expands the number of peripherals
> > that can interrupt the core:
> > * The INTMUX has 8 channels that are assigned to 8 NVIC interrupt slots.
> > * Each INTMUX channel can receive up to 32 interrupt sources and has 1
> >   interrupt output.
> > * The INTMUX routes the interrupt sources to the interrupt outputs.
> >
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
> > ---
> >  drivers/irqchip/Kconfig          |   6 +
> >  drivers/irqchip/Makefile         |   1 +
> >  drivers/irqchip/irq-imx-intmux.c | 311
> > +++++++++++++++++++++++++++++++
> >  3 files changed, 318 insertions(+)
> >  create mode 100644 drivers/irqchip/irq-imx-intmux.c
> >
> > diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig index
> > ba152954324b..7e2b1e9d0b45 100644
> > --- a/drivers/irqchip/Kconfig
> > +++ b/drivers/irqchip/Kconfig
> > @@ -457,6 +457,12 @@ config IMX_IRQSTEER
> >  	help
> >  	  Support for the i.MX IRQSTEER interrupt multiplexer/remapper.
> >
> > +config IMX_INTMUX
> > +	def_bool y if ARCH_MXC
> > +	select IRQ_DOMAIN
> > +	help
> > +	  Support for the i.MX INTMUX interrupt multiplexer.
> > +
> >  config LS1X_IRQ
> >  	bool "Loongson-1 Interrupt Controller"
> >  	depends on MACH_LOONGSON32
> > diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile index
> > e806dda690ea..af976a79d1fb 100644
> > --- a/drivers/irqchip/Makefile
> > +++ b/drivers/irqchip/Makefile
> > @@ -100,6 +100,7 @@ obj-$(CONFIG_CSKY_MPINTC)		+=
> irq-csky-mpintc.o
> >  obj-$(CONFIG_CSKY_APB_INTC)		+= irq-csky-apb-intc.o
> >  obj-$(CONFIG_SIFIVE_PLIC)		+= irq-sifive-plic.o
> >  obj-$(CONFIG_IMX_IRQSTEER)		+= irq-imx-irqsteer.o
> > +obj-$(CONFIG_IMX_INTMUX)		+= irq-imx-intmux.o
> >  obj-$(CONFIG_MADERA_IRQ)		+= irq-madera.o
> >  obj-$(CONFIG_LS1X_IRQ)			+= irq-ls1x.o
> >  obj-$(CONFIG_TI_SCI_INTR_IRQCHIP)	+= irq-ti-sci-intr.o
> > diff --git a/drivers/irqchip/irq-imx-intmux.c
> > b/drivers/irqchip/irq-imx-intmux.c
> > new file mode 100644
> > index 000000000000..94c67fdd7163
> > --- /dev/null
> > +++ b/drivers/irqchip/irq-imx-intmux.c
> > @@ -0,0 +1,311 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +// Copyright 2017 NXP
> > +
> > +/*                     INTMUX Block Diagram
> > + *
> > + *                               ________________
> > + * interrupt source #  0  +---->|                |
> > + *                        |     |                |
> > + * interrupt source #  1  +++-->|                |
> > + *            ...         | |   |   channel # 0  |--------->interrupt out
> # 0
> > + *            ...         | |   |                |
> > + *            ...         | |   |                |
> > + * interrupt source # X-1 +++-->|________________|
> > + *                        | | |
> > + *                        | | |
> > + *                        | | |  ________________
> > + *                        +---->|                |
> > + *                        | | | |                |
> > + *                        | +-->|                |
> > + *                        | | | |   channel # 1  |--------->interrupt out
> # 1
> > + *                        | | +>|                |
> > + *                        | | | |                |
> > + *                        | | | |________________|
> > + *                        | | |
> > + *                        | | |
> > + *                        | | |       ...
> > + *                        | | |       ...
> > + *                        | | |
> > + *                        | | |  ________________
> > + *                        +---->|                |
> > + *                          | | |                |
> > + *                          +-->|                |
> > + *                            | |   channel # N  |--------->interrupt
> out # N
> > + *                            +>|                |
> > + *                              |                |
> > + *                              |________________|
> > + *
> > + *
> > + * N: Interrupt Channel Instance Number (N=7)
> > + * X: Interrupt Source Number for each channel (X=32)
> > + *
> > + * The INTMUX interrupt multiplexer has 8 channels, each channel
> > +receives 32
> > + * interrupt sources and generates 1 interrupt output.
> 
> Does the user care to which channel does the interrupt source goes to? If not,
> interrupt-cells in DT can just be a single entry and the channel selection can be
> controlled by the driver no? I am trying to understand why user should specify
> the channel no.
Hi Lokesh,

If a fixed channel is specified in the driver, all interrupt sources will be connected to this channel, affecting the interrupt priority to some extent.

From my point of view, a fixed channel could be enough if don't care interrupt priority.

Best Regards,
Joakim Zhang
> Thanks and regards,
> Lokesh
> 
> > + *
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/irq.h>
> > +#include <linux/irqchip/chained_irq.h> #include <linux/irqdomain.h>
> > +#include <linux/kernel.h> #include <linux/of_irq.h> #include
> > +<linux/of_platform.h> #include <linux/spinlock.h>
> > +
> > +#define CHANIER(n)	(0x10 + (0x40 * n))
> > +#define CHANIPR(n)	(0x20 + (0x40 * n))
> > +
> > +#define CHAN_MAX_NUM		0x8
> > +
> > +struct intmux_irqchip_data {
> > +	int			chanidx;
> > +	int			irq;
> > +	struct irq_domain	*domain;
> > +};
> > +
> > +struct intmux_data {
> > +	raw_spinlock_t			lock;
> > +	void __iomem			*regs;
> > +	struct clk			*ipg_clk;
> > +	int				channum;
> > +	struct intmux_irqchip_data	irqchip_data[];
> > +};
> > +
> > +static void imx_intmux_irq_mask(struct irq_data *d) {
> > +	struct intmux_irqchip_data *irqchip_data = d->chip_data;
> > +	int idx = irqchip_data->chanidx;
> > +	struct intmux_data *data = container_of(irqchip_data, struct
> intmux_data,
> > +						irqchip_data[idx]);
> > +	unsigned long flags;
> > +	void __iomem *reg;
> > +	u32 val;
> > +
> > +	raw_spin_lock_irqsave(&data->lock, flags);
> > +	reg = data->regs + CHANIER(idx);
> > +	val = readl_relaxed(reg);
> > +	/* disable the interrupt source of this channel */
> > +	val &= ~BIT(d->hwirq);
> > +	writel_relaxed(val, reg);
> > +	raw_spin_unlock_irqrestore(&data->lock, flags); }
> > +
> > +static void imx_intmux_irq_unmask(struct irq_data *d) {
> > +	struct intmux_irqchip_data *irqchip_data = d->chip_data;
> > +	int idx = irqchip_data->chanidx;
> > +	struct intmux_data *data = container_of(irqchip_data, struct
> intmux_data,
> > +						irqchip_data[idx]);
> > +	unsigned long flags;
> > +	void __iomem *reg;
> > +	u32 val;
> > +
> > +	raw_spin_lock_irqsave(&data->lock, flags);
> > +	reg = data->regs + CHANIER(idx);
> > +	val = readl_relaxed(reg);
> > +	/* enable the interrupt source of this channel */
> > +	val |= BIT(d->hwirq);
> > +	writel_relaxed(val, reg);
> > +	raw_spin_unlock_irqrestore(&data->lock, flags); }
> > +
> > +static struct irq_chip imx_intmux_irq_chip = {
> > +	.name		= "intmux",
> > +	.irq_mask	= imx_intmux_irq_mask,
> > +	.irq_unmask	= imx_intmux_irq_unmask,
> > +};
> > +
> > +static int imx_intmux_irq_map(struct irq_domain *h, unsigned int irq,
> > +			      irq_hw_number_t hwirq)
> > +{
> > +	irq_set_status_flags(irq, IRQ_LEVEL);
> > +	irq_set_chip_data(irq, h->host_data);
> > +	irq_set_chip_and_handler(irq, &imx_intmux_irq_chip,
> > +handle_level_irq);
> > +
> > +	return 0;
> > +}
> > +
> > +static int imx_intmux_irq_xlate(struct irq_domain *d, struct device_node
> *node,
> > +				const u32 *intspec, unsigned int intsize,
> > +				unsigned long *out_hwirq, unsigned int *out_type) {
> > +	struct intmux_irqchip_data *irqchip_data = d->host_data;
> > +	int idx = irqchip_data->chanidx;
> > +	struct intmux_data *data = container_of(irqchip_data, struct
> intmux_data,
> > +						irqchip_data[idx]);
> > +
> > +	/* two cells needed in interrupt specifier:
> > +	 * the 1st cell: hw interrupt number
> > +	 * the 2nd cell: channel index
> > +	 */
> > +	if (WARN_ON(intsize != 2))
> > +		return -EINVAL;
> > +
> > +	if (WARN_ON(intspec[1] >= data->channum))
> > +		return -EINVAL;
> > +
> > +	*out_hwirq = intspec[0];
> > +	*out_type = IRQ_TYPE_NONE;
> > +
> > +	return 0;
> > +}
> > +
> > +static int imx_intmux_irq_select(struct irq_domain *d, struct irq_fwspec
> *fwspec,
> > +				 enum irq_domain_bus_token bus_token) {
> > +	struct intmux_irqchip_data *irqchip_data = d->host_data;
> > +
> > +	/* Not for us */
> > +	if (fwspec->fwnode != d->fwnode)
> > +		return false;
> > +
> > +	if (irqchip_data->chanidx == fwspec->param[1])
> > +		return true;
> > +	else
> > +		return false;
> > +}
> > +
> > +static const struct irq_domain_ops imx_intmux_domain_ops = {
> > +	.map		= imx_intmux_irq_map,
> > +	.xlate		= imx_intmux_irq_xlate,
> > +	.select		= imx_intmux_irq_select,
> > +};
> > +
> > +static void imx_intmux_irq_handler(struct irq_desc *desc) {
> > +	struct intmux_irqchip_data *irqchip_data =
> irq_desc_get_handler_data(desc);
> > +	int idx = irqchip_data->chanidx;
> > +	struct intmux_data *data = container_of(irqchip_data, struct
> intmux_data,
> > +						irqchip_data[idx]);
> > +	unsigned long irqstat;
> > +	int pos, virq;
> > +
> > +	chained_irq_enter(irq_desc_get_chip(desc), desc);
> > +
> > +	/* read the interrupt source pending status of this channel */
> > +	irqstat = readl_relaxed(data->regs + CHANIPR(idx));
> > +
> > +	for_each_set_bit(pos, &irqstat, 32) {
> > +		virq = irq_find_mapping(irqchip_data->domain, pos);
> > +		if (virq)
> > +			generic_handle_irq(virq);
> > +	}
> > +
> > +	chained_irq_exit(irq_desc_get_chip(desc), desc); }
> > +
> > +static int imx_intmux_probe(struct platform_device *pdev) {
> > +	struct device_node *np = pdev->dev.of_node;
> > +	struct intmux_data *data;
> > +	int channum;
> > +	int i, ret;
> > +
> > +	ret = of_property_read_u32(np, "fsl,intmux_chans", &channum);
> > +	if (ret) {
> > +		channum = 1;
> > +	} else if (channum > CHAN_MAX_NUM) {
> > +		dev_err(&pdev->dev, "supports up to %d multiplex channels\n",
> > +			CHAN_MAX_NUM);
> > +		return -EINVAL;
> > +	}
> > +
> > +	data = devm_kzalloc(&pdev->dev, sizeof(*data) +
> > +			    channum * sizeof(data->irqchip_data[0]), GFP_KERNEL);
> > +	if (!data)
> > +		return -ENOMEM;
> > +
> > +	data->regs = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(data->regs)) {
> > +		dev_err(&pdev->dev, "failed to initialize reg\n");
> > +		return PTR_ERR(data->regs);
> > +	}
> > +
> > +	data->ipg_clk = devm_clk_get(&pdev->dev, "ipg");
> > +	if (IS_ERR(data->ipg_clk)) {
> > +		ret = PTR_ERR(data->ipg_clk);
> > +		if (ret != -EPROBE_DEFER)
> > +			dev_err(&pdev->dev, "failed to get ipg clk: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	data->channum = channum;
> > +	raw_spin_lock_init(&data->lock);
> > +
> > +	ret = clk_prepare_enable(data->ipg_clk);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "failed to enable ipg clk: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	for (i = 0; i < channum; i++) {
> > +		data->irqchip_data[i].chanidx = i;
> > +
> > +		data->irqchip_data[i].irq = irq_of_parse_and_map(np, i);
> > +		if (data->irqchip_data[i].irq <= 0) {
> > +			ret = -EINVAL;
> > +			dev_err(&pdev->dev, "failed to get irq\n");
> > +			goto out;
> > +		}
> > +
> > +		data->irqchip_data[i].domain =
> > +			irq_domain_add_linear(np, 32, &imx_intmux_domain_ops,
> > +					      &data->irqchip_data[i]);
> > +		if (!data->irqchip_data[i].domain) {
> > +			ret = -ENOMEM;
> > +			dev_err(&pdev->dev, "failed to create IRQ domain\n");
> > +			goto out;
> > +		}
> > +
> > +		irq_set_chained_handler_and_data(data->irqchip_data[i].irq,
> > +						 imx_intmux_irq_handler,
> > +						 &data->irqchip_data[i]);
> > +
> > +		/* disable interrupt sources of this channel firstly */
> > +		writel_relaxed(0, data->regs + CHANIER(i));
> > +	}
> > +
> > +	platform_set_drvdata(pdev, data);
> > +
> > +	return 0;
> > +out:
> > +	clk_disable_unprepare(data->ipg_clk);
> > +	return ret;
> > +}
> > +
> > +static int imx_intmux_remove(struct platform_device *pdev) {
> > +	struct intmux_data *data = platform_get_drvdata(pdev);
> > +	int i;
> > +
> > +	for (i = 0; i < data->channum; i++) {
> > +		/* clear interrupt sources pending status of this channel */
> > +		writel_relaxed(0, data->regs + CHANIPR(i));
> > +
> > +		irq_set_chained_handler_and_data(data->irqchip_data[i].irq,
> > +						 NULL, NULL);
> > +
> > +		irq_domain_remove(data->irqchip_data[i].domain);
> > +	}
> > +
> > +	clk_disable_unprepare(data->ipg_clk);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id imx_intmux_id[] = {
> > +	{ .compatible = "fsl,imx-intmux", },
> > +	{ /* sentinel */ },
> > +};
> > +
> > +static struct platform_driver imx_intmux_driver = {
> > +	.driver = {
> > +		.name = "imx-intmux",
> > +		.of_match_table = imx_intmux_id,
> > +	},
> > +	.probe = imx_intmux_probe,
> > +	.remove = imx_intmux_remove,
> > +};
> > +builtin_platform_driver(imx_intmux_driver);
> >