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Date:   Wed, 29 Jun 2022 11:58:58 +0100
Message-ID: <87wncz20st.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Jianmin Lv <lvjianmin@loongson.cn>
Cc:     Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        Hanjun Guo <guohanjun@huawei.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Huacai Chen <chenhuacai@loongson.cn>
Subject: Re: [PATCH V13 05/13] irqchip: Add Loongson PCH LPC controller support
In-Reply-To: <1656329997-20524-6-git-send-email-lvjianmin@loongson.cn>
References: <1656329997-20524-1-git-send-email-lvjianmin@loongson.cn>
        <1656329997-20524-6-git-send-email-lvjianmin@loongson.cn>
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On Mon, 27 Jun 2022 12:39:49 +0100,
Jianmin Lv <lvjianmin@loongson.cn> wrote:
> 
> From: Huacai Chen <chenhuacai@loongson.cn>
> 
> PCH-LPC stands for "LPC Interrupts" that described in Section 24.3 of
> "Loongson 7A1000 Bridge User Manual". For more information please refer
> Documentation/loongarch/irq-chip-model.rst.
> 
> Co-developed-by: Jianmin Lv <lvjianmin@loongson.cn>
> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> ---
>  arch/loongarch/include/asm/irq.h       |   4 +-
>  arch/loongarch/kernel/irq.c            |   1 -
>  drivers/irqchip/Kconfig                |   8 ++
>  drivers/irqchip/Makefile               |   1 +
>  drivers/irqchip/irq-loongson-pch-lpc.c | 203 +++++++++++++++++++++++++++++++++
>  5 files changed, 214 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/irqchip/irq-loongson-pch-lpc.c
> 
> diff --git a/arch/loongarch/include/asm/irq.h b/arch/loongarch/include/asm/irq.h
> index ace3ea6..48c0ce4 100644
> --- a/arch/loongarch/include/asm/irq.h
> +++ b/arch/loongarch/include/asm/irq.h
> @@ -104,7 +104,7 @@ struct irq_domain *eiointc_acpi_init(struct irq_domain *parent,
>  
>  struct irq_domain *htvec_acpi_init(struct irq_domain *parent,
>  					struct acpi_madt_ht_pic *acpi_htvec);
> -struct irq_domain *pch_lpc_acpi_init(struct irq_domain *parent,
> +int pch_lpc_acpi_init(struct irq_domain *parent,
>  					struct acpi_madt_lpc_pic *acpi_pchlpc);
>  struct irq_domain *pch_msi_acpi_init(struct irq_domain *parent,
>  					struct acpi_madt_msi_pic *acpi_pchmsi);
> @@ -121,7 +121,7 @@ struct irq_domain *pch_pic_acpi_init(struct irq_domain *parent,
>  
>  extern struct irq_domain *cpu_domain;
>  extern struct irq_domain *liointc_domain;
> -extern struct irq_domain *pch_lpc_domain;
> +extern struct fwnode_handle *pch_lpc_handle;
>  extern struct irq_domain *pch_msi_domain[MAX_IO_PICS];
>  extern struct irq_domain *pch_pic_domain[MAX_IO_PICS];
>  
> diff --git a/arch/loongarch/kernel/irq.c b/arch/loongarch/kernel/irq.c
> index b34b8d7..07d6059 100644
> --- a/arch/loongarch/kernel/irq.c
> +++ b/arch/loongarch/kernel/irq.c
> @@ -27,7 +27,6 @@
>  
>  struct irq_domain *cpu_domain;
>  struct irq_domain *liointc_domain;
> -struct irq_domain *pch_lpc_domain;
>  struct irq_domain *pch_msi_domain[MAX_IO_PICS];
>  struct irq_domain *pch_pic_domain[MAX_IO_PICS];
>  
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 1f23a6b..c1d527f 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -591,6 +591,14 @@ config LOONGSON_PCH_MSI
>  	help
>  	  Support for the Loongson PCH MSI Controller.
>  
> +config LOONGSON_PCH_LPC
> +	bool "Loongson PCH LPC Controller"
> +	depends on MACH_LOONGSON64
> +	default (MACH_LOONGSON64 && LOONGARCH)
> +	select IRQ_DOMAIN_HIERARCHY
> +	help
> +	  Support for the Loongson PCH LPC Controller.
> +
>  config MST_IRQ
>  	bool "MStar Interrupt Controller"
>  	depends on ARCH_MEDIATEK || ARCH_MSTARV7 || COMPILE_TEST
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 5b67450..242b8b3 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -108,6 +108,7 @@ obj-$(CONFIG_LOONGSON_HTPIC)		+= irq-loongson-htpic.o
>  obj-$(CONFIG_LOONGSON_HTVEC)		+= irq-loongson-htvec.o
>  obj-$(CONFIG_LOONGSON_PCH_PIC)		+= irq-loongson-pch-pic.o
>  obj-$(CONFIG_LOONGSON_PCH_MSI)		+= irq-loongson-pch-msi.o
> +obj-$(CONFIG_LOONGSON_PCH_LPC)		+= irq-loongson-pch-lpc.o
>  obj-$(CONFIG_MST_IRQ)			+= irq-mst-intc.o
>  obj-$(CONFIG_SL28CPLD_INTC)		+= irq-sl28cpld.o
>  obj-$(CONFIG_MACH_REALTEK_RTL)		+= irq-realtek-rtl.o
> diff --git a/drivers/irqchip/irq-loongson-pch-lpc.c b/drivers/irqchip/irq-loongson-pch-lpc.c
> new file mode 100644
> index 0000000..7e4d89a
> --- /dev/null
> +++ b/drivers/irqchip/irq-loongson-pch-lpc.c
> @@ -0,0 +1,203 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Loongson LPC Interrupt Controller support
> + *
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +
> +#define pr_fmt(fmt) "lpc: " fmt
> +
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/kernel.h>
> +
> +/* Registers */
> +#define LPC_INT_CTL		0x00
> +#define LPC_INT_ENA		0x04
> +#define LPC_INT_STS		0x08
> +#define LPC_INT_CLR		0x0c
> +#define LPC_INT_POL		0x10
> +#define LPC_COUNT		16
> +
> +struct pch_lpc {
> +	void __iomem		*base;
> +	struct irq_domain	*lpc_domain;
> +	raw_spinlock_t		lpc_lock;
> +	u32			saved_reg_ctl;
> +	u32			saved_reg_ena;
> +	u32			saved_reg_pol;
> +};
> +
> +struct fwnode_handle *pch_lpc_handle;
> +
> +static void ack_lpc_irq(struct irq_data *d)
> +{
> +	unsigned long flags;
> +	struct pch_lpc *priv = d->domain->host_data;
> +
> +	raw_spin_lock_irqsave(&priv->lpc_lock, flags);
> +	writel(0x1 << d->hwirq, priv->base + LPC_INT_CLR);
> +	raw_spin_unlock_irqrestore(&priv->lpc_lock, flags);
> +}
> +static void mask_lpc_irq(struct irq_data *d)
> +{
> +	unsigned long flags;
> +	struct pch_lpc *priv = d->domain->host_data;
> +
> +	raw_spin_lock_irqsave(&priv->lpc_lock, flags);
> +	writel(readl(priv->base + LPC_INT_ENA) & (~(0x1 << (d->hwirq))),
> +			priv->base + LPC_INT_ENA);
> +	raw_spin_unlock_irqrestore(&priv->lpc_lock, flags);
> +}
> +
> +static void unmask_lpc_irq(struct irq_data *d)
> +{
> +	unsigned long flags;
> +	struct pch_lpc *priv = d->domain->host_data;
> +
> +	raw_spin_lock_irqsave(&priv->lpc_lock, flags);
> +	writel(readl(priv->base + LPC_INT_ENA) | (0x1 << (d->hwirq)),
> +			priv->base + LPC_INT_ENA);
> +	raw_spin_unlock_irqrestore(&priv->lpc_lock, flags);
> +}
> +
> +static int lpc_set_type(struct irq_data *d, unsigned int type)
> +{
> +	u32 val;
> +	u32 mask = 0x1 << (d->hwirq);
> +	struct pch_lpc *priv = d->domain->host_data;
> +
> +	if (!(type & IRQ_TYPE_LEVEL_MASK))
> +		return 0;
> +
> +	val = readl(priv->base + LPC_INT_POL);
> +
> +	if (type == IRQ_TYPE_LEVEL_HIGH)
> +		val |= mask;
> +	else
> +		val &= ~mask;
> +
> +	writel(val, priv->base + LPC_INT_POL);
> +
> +	return 0;
> +}
> +
> +static struct irq_chip pch_lpc_irq_chip = {

Make this const.

> +	.name			= "PCH LPC",
> +	.irq_mask		= mask_lpc_irq,
> +	.irq_unmask		= unmask_lpc_irq,
> +	.irq_ack		= ack_lpc_irq,
> +	.irq_set_type		= lpc_set_type,

nit: please use the same format for all callbacks: lpc_irq_OPERATION
(lpc_irq_mask, lpc_irq_set_type...), which makes it much easier to
read.

> +	.flags			= IRQCHIP_SKIP_SET_WAKE,
> +};
> +
> +static void lpc_irq_dispatch(struct irq_desc *desc)
> +{
> +	u32 pending, bit, virq;
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	struct pch_lpc *priv = irq_desc_get_handler_data(desc);
> +
> +	chained_irq_enter(chip, desc);
> +
> +	pending = readl(priv->base + LPC_INT_ENA);
> +	pending &= readl(priv->base + LPC_INT_STS);
> +	if (!pending)
> +		spurious_interrupt();
> +
> +	while (pending) {
> +		bit = __ffs(pending);
> +		virq = irq_linear_revmap(priv->lpc_domain, bit);
> +
> +		generic_handle_irq(bit);

Replace the whole thing with a call to generic_handle_domain_irq(). No
new code should ever have to use generic_handle_irq().

> +		pending &= ~BIT(bit);
> +	}
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static int pch_lpc_map(struct irq_domain *d, unsigned int irq,
> +			irq_hw_number_t hw)
> +{
> +	irq_set_chip_and_handler(irq, &pch_lpc_irq_chip, handle_level_irq);
> +	return 0;
> +}
> +
> +static const struct irq_domain_ops pch_lpc_domain_ops = {
> +	.map 		= pch_lpc_map,
> +	.translate	= irq_domain_translate_twocell,
> +};
> +
> +static void pch_lpc_reset(struct pch_lpc *priv)
> +{
> +	/* Enable the LPC interrupt, bit31: en  bit30: edge */
> +	writel(0x80000000, priv->base + LPC_INT_CTL);

Please don't hardcode numbers. Add the proper bit definitions.

> +	writel(0, priv->base + LPC_INT_ENA);
> +	/* Clear all 18-bit interrpt bit */
> +	writel(0x3ffff, priv->base + LPC_INT_CLR);

If that's just a mask, then use GENMASK(17, 0) instead.

> +}
> +
> +static int pch_lpc_disabled(struct pch_lpc *priv)
> +{
> +	return (readl(priv->base + LPC_INT_ENA) == 0xffffffff) &&
> +			(readl(priv->base + LPC_INT_STS) == 0xffffffff);
> +}
> +
> +int __init pch_lpc_acpi_init(struct irq_domain *parent,
> +					struct acpi_madt_lpc_pic *acpi_pchlpc)
> +{
> +	int parent_irq;
> +	struct pch_lpc *priv;
> +	struct irq_fwspec fwspec;
> +	struct fwnode_handle *irq_handle;
> +
> +	if (!acpi_pchlpc)
> +		return -EINVAL;
> +
> +	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	raw_spin_lock_init(&priv->lpc_lock);
> +
> +	priv->base = ioremap(acpi_pchlpc->address, acpi_pchlpc->size);
> +	if (!priv->base)
> +		goto free_priv;
> +
> +	if (pch_lpc_disabled(priv)) {
> +		pr_err("Failed to get LPC status\n");
> +		goto iounmap_base;
> +	}
> +
> +	irq_handle = irq_domain_alloc_named_fwnode("lpcintc");
> +	if (!irq_handle) {
> +		pr_err("Unable to allocate domain handle\n");
> +		goto iounmap_base;
> +	}
> +
> +	priv->lpc_domain = irq_domain_create_linear(irq_handle, LPC_COUNT,
> +					&pch_lpc_domain_ops, priv);
> +	if (!priv->lpc_domain) {
> +		pr_err("Failed to create IRQ domain\n");
> +		goto iounmap_base;

You also need to free the fwnode.

> +	}
> +	pch_lpc_reset(priv);
> +
> +	fwspec.fwnode = parent->fwnode;
> +	fwspec.param[0] = acpi_pchlpc->cascade;
> +	fwspec.param[1] = IRQ_TYPE_LEVEL_HIGH;
> +	fwspec.param_count = 2;
> +	parent_irq = irq_create_fwspec_mapping(&fwspec);
> +	irq_set_chained_handler_and_data(parent_irq, lpc_irq_dispatch, priv);
> +
> +	pch_lpc_handle = irq_handle;
> +	return 0;
> +
> +iounmap_base:
> +	iounmap(priv->base);
> +free_priv:
> +	kfree(priv);
> +
> +	return -ENOMEM;
> +}
> -- 
> 1.8.3.1
> 
> 

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.