RE: [PATCH 4/6] irqchip/aspeed: Add Aspeed eSPI interrupt controller

[ChiaWei Wang]

Hi Marc,

I will revise the patch as suggested.
Thanks for the feedback.

Chiawei

> -----Original Message-----
> From: Marc Zyngier <maz@xxxxxxxxxx>
> Sent: Thursday, January 7, 2021 6:18 PM
> To: ChiaWei Wang <chiawei_wang@xxxxxxxxxxxxxx>
> <BMC-SW@xxxxxxxxxxxxxx>
> Subject: Re: [PATCH 4/6] irqchip/aspeed: Add Aspeed eSPI interrupt controller
> 
> On 2021-01-07 02:59, ChiaWei Wang wrote:
> > Hi Marc,
> >
> >> -----Original Message-----
> >> From: Marc Zyngier <maz@xxxxxxxxxx>
> >> Sent: Wednesday, January 6, 2021 6:59 PM
> >> To: ChiaWei Wang <chiawei_wang@xxxxxxxxxxxxxx>
> >> Subject: Re: [PATCH 4/6] irqchip/aspeed: Add Aspeed eSPI interrupt
> >> controller
> >>
> >> On 2021-01-06 05:59, Chia-Wei, Wang wrote:
> >> > The eSPI interrupt controller acts as a SW IRQ number decoder to
> >> > correctly control/dispatch interrupts of the eSPI peripheral,
> >> > virtual wire, out-of-band, and flash channels.
> >> >
> >> > Signed-off-by: Chia-Wei, Wang <chiawei_wang@xxxxxxxxxxxxxx>
> >> > ---
> >> >  drivers/irqchip/Makefile             |   2 +-
> >> >  drivers/irqchip/irq-aspeed-espi-ic.c | 251 ++++++++++++++++++++++++
> >> >  include/soc/aspeed/espi.h            | 279
> >> +++++++++++++++++++++++++++
> >> >  3 files changed, 531 insertions(+), 1 deletion(-)  create mode
> >> > 100644 drivers/irqchip/irq-aspeed-espi-ic.c
> >> >  create mode 100644 include/soc/aspeed/espi.h
> >> >
> >> > diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> >> > index
> >> > 0ac93bfaec61..56da4a3123f8 100644
> >> > --- a/drivers/irqchip/Makefile
> >> > +++ b/drivers/irqchip/Makefile
> >> > @@ -86,7 +86,7 @@ obj-$(CONFIG_MVEBU_PIC)			+=
> >> irq-mvebu-pic.o
> >> >  obj-$(CONFIG_MVEBU_SEI)			+= irq-mvebu-sei.o
> >> >  obj-$(CONFIG_LS_EXTIRQ)			+= irq-ls-extirq.o
> >> >  obj-$(CONFIG_LS_SCFG_MSI)		+= irq-ls-scfg-msi.o
> >> > -obj-$(CONFIG_ARCH_ASPEED)		+= irq-aspeed-vic.o
> irq-aspeed-i2c-ic.o
> >> > irq-aspeed-scu-ic.o
> >> > +obj-$(CONFIG_ARCH_ASPEED)		+= irq-aspeed-vic.o
> irq-aspeed-i2c-ic.o
> >> > irq-aspeed-scu-ic.o irq-aspeed-espi-ic.o
> >> >  obj-$(CONFIG_STM32_EXTI) 		+= irq-stm32-exti.o
> >> >  obj-$(CONFIG_QCOM_IRQ_COMBINER)		+= qcom-irq-combiner.o
> >> >  obj-$(CONFIG_IRQ_UNIPHIER_AIDET)	+= irq-uniphier-aidet.o
> >> > diff --git a/drivers/irqchip/irq-aspeed-espi-ic.c
> >> > b/drivers/irqchip/irq-aspeed-espi-ic.c
> >> > new file mode 100644
> >> > index 000000000000..8a5cc8fe3f0c
> >> > --- /dev/null
> >> > +++ b/drivers/irqchip/irq-aspeed-espi-ic.c
> >> > @@ -0,0 +1,251 @@
> >> > +// SPDX-License-Identifier: GPL-2.0-or-later
> >> > +/*
> >> > + * Copyright (c) 2020 Aspeed Technology Inc.
> >> > + */
> >> > +#include <linux/bitops.h>
> >> > +#include <linux/module.h>
> >> > +#include <linux/irq.h>
> >> > +#include <linux/irqchip.h>
> >> > +#include <linux/irqchip/chained_irq.h> #include
> >> > +<linux/irqdomain.h> #include <linux/interrupt.h> #include
> >> > +<linux/mfd/syscon.h> #include <linux/regmap.h> #include
> >> > +<linux/of.h> #include <linux/of_platform.h>
> >> > +
> >> > +#include <soc/aspeed/espi.h>
> >> > +#include <dt-bindings/interrupt-controller/aspeed-espi-ic.h>
> >> > +
> >> > +#define DEVICE_NAME	"aspeed-espi-ic"
> >> > +#define IRQCHIP_NAME	"eSPI-IC"
> >> > +
> >> > +#define ESPI_IC_IRQ_NUM	7
> >> > +
> >> > +struct aspeed_espi_ic {
> >> > +	struct regmap *map;
> >> > +	int irq;
> >> > +	int gpio_irq;
> >> > +	struct irq_domain *irq_domain;
> >> > +};
> >> > +
> >> > +static void aspeed_espi_ic_gpio_isr(struct irq_desc *desc) {
> >> > +	unsigned int irq;
> >> > +	struct aspeed_espi_ic *espi_ic = irq_desc_get_handler_data(desc);
> >> > +	struct irq_chip *chip = irq_desc_get_chip(desc);
> >> > +
> >> > +	chained_irq_enter(chip, desc);
> >> > +
> >> > +	irq = irq_find_mapping(espi_ic->irq_domain,
> >> > +				   ASPEED_ESPI_IC_CTRL_RESET);
> >> > +	generic_handle_irq(irq);
> >> > +
> >> > +	irq = irq_find_mapping(espi_ic->irq_domain,
> >> > +				   ASPEED_ESPI_IC_CHAN_RESET);
> >> > +	generic_handle_irq(irq);
> >>
> >> So for each mux interrupt, you generate two endpoints interrupt,
> >> without even checking whether they are pending? That's no good.
> >
> > As the eSPI IC driver is chained to Aspeed GPIO IC, the pending is
> > checked in the gpio-aspeed.c
> 
> That's not the place to do that.
> 
> >
> >> > +
> >> > +	chained_irq_exit(chip, desc);
> >> > +}
> >> > +
> >> > +static void aspeed_espi_ic_isr(struct irq_desc *desc) {
> >> > +	unsigned int sts;
> >> > +	unsigned int irq;
> >> > +	struct aspeed_espi_ic *espi_ic = irq_desc_get_handler_data(desc);
> >> > +	struct irq_chip *chip = irq_desc_get_chip(desc);
> >> > +
> >> > +	chained_irq_enter(chip, desc);
> >> > +
> >> > +	regmap_read(espi_ic->map, ESPI_INT_STS, &sts);
> >> > +
> >> > +	if (sts & ESPI_INT_STS_PERIF_BITS) {
> >> > +		irq = irq_find_mapping(espi_ic->irq_domain,
> >> > +				       ASPEED_ESPI_IC_PERIF_EVENT);
> >> > +		generic_handle_irq(irq);
> >> > +	}
> >> > +
> >> > +	if (sts & ESPI_INT_STS_VW_BITS) {
> >> > +		irq = irq_find_mapping(espi_ic->irq_domain,
> >> > +				       ASPEED_ESPI_IC_VW_EVENT);
> >> > +		generic_handle_irq(irq);
> >> > +	}
> >> > +
> >> > +	if (sts & ESPI_INT_STS_OOB_BITS) {
> >> > +		irq = irq_find_mapping(espi_ic->irq_domain,
> >> > +				       ASPEED_ESPI_IC_OOB_EVENT);
> >> > +		generic_handle_irq(irq);
> >> > +	}
> >> > +
> >> > +	if (sts & ESPI_INT_STS_FLASH_BITS) {
> >> > +		irq = irq_find_mapping(espi_ic->irq_domain,
> >> > +				       ASPEED_ESPI_IC_FLASH_EVENT);
> >> > +		generic_handle_irq(irq);
> >> > +	}
> >> > +
> >> > +	if (sts & ESPI_INT_STS_HW_RST_DEASSERT) {
> >> > +		irq = irq_find_mapping(espi_ic->irq_domain,
> >> > +				       ASPEED_ESPI_IC_CTRL_EVENT);
> >> > +		generic_handle_irq(irq);
> >> > +	}
> >>
> >> This is horrible. Why can't you just use fls() in a loop?
> >
> > The bits in the interrupt status register for a eSPI channel are not
> > sequentially arranged.
> > Using fls() may invoke an eSPI channel ISR multiple times.
> > So I collected the bitmap for each channel, respectively, and call the
> > ISR at once.
> 
> And that's equally wrong. You need to handle interrupts individually, as they
> are different signal. If you are to implement an interrupt controller, please do it
> properly.
> 
> Otherwise, get rid of it and move everything into your pet driver.
> There is no need to do a half-baked job.
> 
> As it is, there is no way this code can be merged.
> 
>          M.
> --
> Jazz is not dead. It just smells funny...