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Message-ID: <54AA53C2.9040903@arm.com>
Date: Mon, 05 Jan 2015 09:05:06 +0000
From: Marc Zyngier <marc.zyngier@....com>
To: Liviu Dudau <Liviu.Dudau@....com>,
Russell King <linux@....linux.org.uk>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <Mark.Rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Thomas Gleixner <tglx@...utronix.de>,
Jason Cooper <jason@...edaemon.net>,
Haojian Zhuang <haojian.zhuang@...aro.org>
CC: "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
LAKML <linux-arm-kernel@...ts.infradead.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] irqchip: gic: Allow interrupt level to be set for
PPIs.
Hi Liviu,
On 01/12/14 12:45, Liviu Dudau wrote:
> During a recent cleanup of the arm64 DTs it has become clear that
> the handling of PPIs in xxxx_set_type() is incorrect. The ARM TRMs
> for GICv2 and later allow for "implementation defined" support for
> setting the edge or level type of the PPI interrupts and don't restrict
> the activation level of the signal. Current ARM implementations
> do restrict the PPI level type to IRQ_TYPE_LEVEL_LOW, but licensees
> of the IP can decide to shoot themselves in the foot at any time.
>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
> ---
>
> Made a stupid mistake in v2 and got my bit test confused with logical test.
>
> Documentation/devicetree/bindings/arm/gic.txt | 8 ++++++--
> drivers/irqchip/irq-gic-common.c | 21 +++++++++++++--------
> drivers/irqchip/irq-gic-common.h | 2 +-
> drivers/irqchip/irq-gic-v3.c | 8 ++++----
> drivers/irqchip/irq-gic.c | 9 ++++++---
> drivers/irqchip/irq-hip04.c | 9 ++++++---
> 6 files changed, 36 insertions(+), 21 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/arm/gic.txt b/Documentation/devicetree/bindings/arm/gic.txt
> index 8112d0c..c97484b 100644
> --- a/Documentation/devicetree/bindings/arm/gic.txt
> +++ b/Documentation/devicetree/bindings/arm/gic.txt
> @@ -32,12 +32,16 @@ Main node required properties:
> The 3rd cell is the flags, encoded as follows:
> bits[3:0] trigger type and level flags.
> 1 = low-to-high edge triggered
> - 2 = high-to-low edge triggered
> + 2 = high-to-low edge triggered (invalid for SPIs)
> 4 = active high level-sensitive
> - 8 = active low level-sensitive
> + 8 = active low level-sensitive (invalid for SPIs).
> bits[15:8] PPI interrupt cpu mask. Each bit corresponds to each of
> the 8 possible cpus attached to the GIC. A bit set to '1' indicated
> the interrupt is wired to that CPU. Only valid for PPI interrupts.
> + Also note that the configurability of PPI interrupts is IMPLEMENTATION
> + DEFINED and as such not guaranteed to be present (most SoC available
> + in 2014 seem to ignore the setting of this flag and use the hardware
> + default value).
>
> - reg : Specifies base physical address(s) and size of the GIC registers. The
> first region is the GIC distributor register base and size. The 2nd region is
> diff --git a/drivers/irqchip/irq-gic-common.c b/drivers/irqchip/irq-gic-common.c
> index 61541ff..ffee521 100644
> --- a/drivers/irqchip/irq-gic-common.c
> +++ b/drivers/irqchip/irq-gic-common.c
> @@ -21,7 +21,7 @@
>
> #include "irq-gic-common.h"
>
> -void gic_configure_irq(unsigned int irq, unsigned int type,
> +int gic_configure_irq(unsigned int irq, unsigned int type,
> void __iomem *base, void (*sync_access)(void))
> {
> u32 enablemask = 1 << (irq % 32);
> @@ -29,16 +29,17 @@ void gic_configure_irq(unsigned int irq, unsigned int type,
> u32 confmask = 0x2 << ((irq % 16) * 2);
> u32 confoff = (irq / 16) * 4;
> bool enabled = false;
> - u32 val;
> + u32 val, oldval;
> + int ret = 0;
>
> /*
> * Read current configuration register, and insert the config
> * for "irq", depending on "type".
> */
> - val = readl_relaxed(base + GIC_DIST_CONFIG + confoff);
> - if (type == IRQ_TYPE_LEVEL_HIGH)
> + val = oldval = readl_relaxed(base + GIC_DIST_CONFIG + confoff);
> + if (type & IRQ_TYPE_LEVEL_MASK)
> val &= ~confmask;
> - else if (type == IRQ_TYPE_EDGE_RISING)
> + else if (type & IRQ_TYPE_EDGE_BOTH)
> val |= confmask;
>
> /*
> @@ -54,15 +55,19 @@ void gic_configure_irq(unsigned int irq, unsigned int type,
>
> /*
> * Write back the new configuration, and possibly re-enable
> - * the interrupt.
> + * the interrupt. If we tried to write a new configuration and failed,
> + * return an error.
> */
> writel_relaxed(val, base + GIC_DIST_CONFIG + confoff);
> -
> - if (enabled)
> + if (readl_relaxed(base + GIC_DIST_CONFIG + confoff) != val && val != oldval)
> + ret = -EINVAL;
> + else if (enabled)
> writel_relaxed(enablemask, base + GIC_DIST_ENABLE_SET + enableoff);
So if you change the configuration of an enabled interrupt and fail to
do so, you end-up with the interrupt disabled. This is a change in
behaviour, and is likely to introduce regressions.
>
> if (sync_access)
> sync_access();
> +
> + return ret;
> }
>
> void __init gic_dist_config(void __iomem *base, int gic_irqs,
> diff --git a/drivers/irqchip/irq-gic-common.h b/drivers/irqchip/irq-gic-common.h
> index b41f024..35a9884 100644
> --- a/drivers/irqchip/irq-gic-common.h
> +++ b/drivers/irqchip/irq-gic-common.h
> @@ -20,7 +20,7 @@
> #include <linux/of.h>
> #include <linux/irqdomain.h>
>
> -void gic_configure_irq(unsigned int irq, unsigned int type,
> +int gic_configure_irq(unsigned int irq, unsigned int type,
> void __iomem *base, void (*sync_access)(void));
> void gic_dist_config(void __iomem *base, int gic_irqs,
> void (*sync_access)(void));
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 1a146cc..6e50803 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -238,7 +238,9 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
> if (irq < 16)
> return -EINVAL;
>
> - if (type != IRQ_TYPE_LEVEL_HIGH && type != IRQ_TYPE_EDGE_RISING)
> + /* SPIs have restrictions on the supported types */
> + if (irq >= 32 && type != IRQ_TYPE_LEVEL_HIGH &&
> + type != IRQ_TYPE_EDGE_RISING)
> return -EINVAL;
>
> if (gic_irq_in_rdist(d)) {
> @@ -249,9 +251,7 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
> rwp_wait = gic_dist_wait_for_rwp;
> }
>
> - gic_configure_irq(irq, type, base, rwp_wait);
> -
> - return 0;
> + return gic_configure_irq(irq, type, base, rwp_wait);
> }
>
> static u64 gic_mpidr_to_affinity(u64 mpidr)
> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> index d617ee5..4634cf7 100644
> --- a/drivers/irqchip/irq-gic.c
> +++ b/drivers/irqchip/irq-gic.c
> @@ -188,12 +188,15 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
> {
> void __iomem *base = gic_dist_base(d);
> unsigned int gicirq = gic_irq(d);
> + int ret;
>
> /* Interrupt configuration for SGIs can't be changed */
> if (gicirq < 16)
> return -EINVAL;
>
> - if (type != IRQ_TYPE_LEVEL_HIGH && type != IRQ_TYPE_EDGE_RISING)
> + /* SPIs have restrictions on the supported types */
> + if (gicirq >= 32 && type != IRQ_TYPE_LEVEL_HIGH &&
> + type != IRQ_TYPE_EDGE_RISING)
> return -EINVAL;
>
> raw_spin_lock(&irq_controller_lock);
> @@ -201,11 +204,11 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
> if (gic_arch_extn.irq_set_type)
> gic_arch_extn.irq_set_type(d, type);
>
> - gic_configure_irq(gicirq, type, base, NULL);
> + ret = gic_configure_irq(gicirq, type, base, NULL);
>
> raw_spin_unlock(&irq_controller_lock);
>
> - return 0;
> + return ret;
> }
>
> static int gic_retrigger(struct irq_data *d)
> diff --git a/drivers/irqchip/irq-hip04.c b/drivers/irqchip/irq-hip04.c
> index 29b8f21..d059e66 100644
> --- a/drivers/irqchip/irq-hip04.c
> +++ b/drivers/irqchip/irq-hip04.c
> @@ -120,21 +120,24 @@ static int hip04_irq_set_type(struct irq_data *d, unsigned int type)
> {
> void __iomem *base = hip04_dist_base(d);
> unsigned int irq = hip04_irq(d);
> + int ret;
>
> /* Interrupt configuration for SGIs can't be changed */
> if (irq < 16)
> return -EINVAL;
>
> - if (type != IRQ_TYPE_LEVEL_HIGH && type != IRQ_TYPE_EDGE_RISING)
> + /* SPIs have restrictions on the supported types */
> + if (irq >= 32 && type != IRQ_TYPE_LEVEL_HIGH &&
> + type != IRQ_TYPE_EDGE_RISING)
> return -EINVAL;
>
> raw_spin_lock(&irq_controller_lock);
>
> - gic_configure_irq(irq, type, base, NULL);
> + ret = gic_configure_irq(irq, type, base, NULL);
>
> raw_spin_unlock(&irq_controller_lock);
>
> - return 0;
> + return ret;
> }
>
> #ifdef CONFIG_SMP
>
I have exactly zero knowledge about the hip04 controller, and despite it
looking like a GIC, it is quite different from the real thing. I'd like
to see confirmation from the HiSilicon guys that this is the right thing
to do, and possibly this to be moved to a separate patch if that
requires extra changes.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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