Re: [RFC PATCH v3 3/4] irqchip: gic-v3: Add quirk for msm8996 secured registers

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Mon 12 Nov 02:33 PST 2018, Srinivas Kandagatla wrote:

> Access to GICR_WAKER is restricted on msm8996 SoC in Hypervisor.
> Its been more than 2+ years of wait for this to be fixed, which has
> no hopes to be fixed. This change was introduced for the "lead device"
> on msm8996 platform. It looks like all publicly available msm8996 and
> other qcom SoCs have this implementation.
> 
> So add a quirk to not access this register on msm8996.
> 
> With this quirk MSM8996 can at least boot out of mainline,
> which can help community to work with boards based on MSM8996 and other
> SoCs with have this restrictions. This Quirk is based on device tree
> compatible string.
> 
> Without this patch Qualcomm DB820c board reboots when GICR_WAKER
> is accessed.
> 

Hi Srinivas,

Given that the change request introducing this restriction looks quite
generic and that we've heard reports of other shipping platforms having
the same restriction, could we make this slightly more generic?

I.e. dropping the MSM8996 from the flag name and perhaps use a bool
property in devicetree to toggle the flag, instead of adding compatibles
as we figure out which Qualcomm platforms has this restriction.

Regards,
Bjorn

> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
>  drivers/irqchip/irq-gic-v3.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 8f87f40c9460..4bd3bbe1b7ce 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -41,6 +41,8 @@
>  
>  #include "irq-gic-common.h"
>  
> +#define FLAGS_WORKAROUND_GICR_WAKER_MSM8996	(1ULL << 0)
> +
>  struct redist_region {
>  	void __iomem		*redist_base;
>  	phys_addr_t		phys_base;
> @@ -55,6 +57,7 @@ struct gic_chip_data {
>  	struct irq_domain	*domain;
>  	u64			redist_stride;
>  	u32			nr_redist_regions;
> +	u64			flags;
>  	bool			has_rss;
>  	unsigned int		irq_nr;
>  	struct partition_desc	*ppi_descs[16];
> @@ -139,6 +142,9 @@ static void gic_enable_redist(bool enable)
>  	u32 count = 1000000;	/* 1s! */
>  	u32 val;
>  
> +	if (gic_data.flags & FLAGS_WORKAROUND_GICR_WAKER_MSM8996)
> +		return;
> +
>  	rbase = gic_data_rdist_rd_base();
>  
>  	val = readl_relaxed(rbase + GICR_WAKER);
> @@ -1067,6 +1073,23 @@ static const struct irq_domain_ops partition_domain_ops = {
>  	.select = gic_irq_domain_select,
>  };
>  
> +static bool __maybe_unused gic_enable_quirk_msm8996(void *data)
> +{
> +	struct gic_chip_data *d = data;
> +
> +	d->flags |= FLAGS_WORKAROUND_GICR_WAKER_MSM8996;
> +
> +	return true;
> +}
> +
> +static const struct gic_quirk gic_quirks[] = {
> +	{
> +		.desc	= "GICv3: Qualcomm MSM8996 skip GICR_WAKER Read/Write",
> +		.compatible = "qcom,msm8996-gic-v3", /* MSM8996 */
> +		.init	= gic_enable_quirk_msm8996,
> +	},
> +};
> +
>  static int __init gic_init_bases(void __iomem *dist_base,
>  				 struct redist_region *rdist_regs,
>  				 u32 nr_redist_regions,
> @@ -1126,6 +1149,9 @@ static int __init gic_init_bases(void __iomem *dist_base,
>  
>  	gic_update_vlpi_properties();
>  
> +	if (is_of_node(handle))
> +		gic_enable_of_quirks(to_of_node(handle), gic_quirks, &gic_data);
> +
>  	gic_smp_init();
>  	gic_dist_init();
>  	gic_cpu_init();
> -- 
> 2.19.1
>