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[PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section

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  [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section Markos Chandras <markos.chandras@imgtec.com> - 2015-10-12 11:50 +0200
    Re: [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map  GIC user section Marc Zyngier <marc.zyngier@arm.com> - 2015-10-12 12:00 +0200
      Re: [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map  GIC user section Thomas Gleixner <tglx@linutronix.de> - 2015-10-12 12:20 +0200
        Re: [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map GIC  user section Qais Yousef <qais.yousef@imgtec.com> - 2015-10-15 11:40 +0200
          Re: [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map  GIC user section Thomas Gleixner <tglx@linutronix.de> - 2015-10-15 12:20 +0200

#1244552 — [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section

From: Alex Smith <alex.smith@imgtec.com>

The GIC provides a "user-mode visible" section containing a mirror of
the counter registers which can be mapped into user memory. This will
be used by the VDSO time function implementations, so provide a
function to map it in.

When the GIC is not enabled in Kconfig a dummy inline version of this
function is provided, along with "#define gic_present 0", so that we
don't have to litter the VDSO code with ifdefs.

[markos.chandras@imgtec.com:
- Move mapping code to arch/mips/kernel/vdso.c and use a resource
type to get the GIC usermode information
- Avoid renaming function arguments and use __gic_base_addr to hold
the base GIC address prior to ioremap.]

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
---
Changes since v1:
- Move mapping code to arch/mips/kernel/vdso.c and use a resource
type to get the GIC usermode information
- Avoid renaming function arguments and use __gic_base_addr to hold
the base GIC address prior to ioremap.

http://www.linux-mips.org/archives/linux-mips/2015-09/msg00316.html
---
 drivers/irqchip/irq-mips-gic.c   | 14 ++++++++++++++
 include/linux/irqchip/mips-gic.h | 17 +++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index af2f16bb8a94..392beebb81ee 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -29,6 +29,7 @@ struct gic_pcpu_mask {
 	DECLARE_BITMAP(pcpu_mask, GIC_MAX_INTRS);
 };
 
+static unsigned long __gic_base_addr;
 static void __iomem *gic_base;
 static struct gic_pcpu_mask pcpu_masks[NR_CPUS];
 static DEFINE_SPINLOCK(gic_lock);
@@ -301,6 +302,17 @@ int gic_get_c0_fdc_int(void)
 				  GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_FDC));
 }
 
+int gic_get_usm_range(struct resource *gic_usm_res)
+{
+	if (!gic_present)
+		return -1;
+
+	gic_usm_res->start = __gic_base_addr + USM_VISIBLE_SECTION_OFS;
+	gic_usm_res->end = gic_usm_res->start + (USM_VISIBLE_SECTION_SIZE - 1);
+
+	return 0;
+}
+
 static void gic_handle_shared_int(bool chained)
 {
 	unsigned int i, intr, virq, gic_reg_step = mips_cm_is64 ? 8 : 4;
@@ -790,6 +802,8 @@ static void __init __gic_init(unsigned long gic_base_addr,
 {
 	unsigned int gicconfig;
 
+	__gic_base_addr = gic_base_addr;
+
 	gic_base = ioremap_nocache(gic_base_addr, gic_addrspace_size);
 
 	gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG));
diff --git a/include/linux/irqchip/mips-gic.h b/include/linux/irqchip/mips-gic.h
index 4e6861605050..71ab7c548550 100644
--- a/include/linux/irqchip/mips-gic.h
+++ b/include/linux/irqchip/mips-gic.h
@@ -9,6 +9,7 @@
 #define __LINUX_IRQCHIP_MIPS_GIC_H
 
 #include <linux/clocksource.h>
+#include <linux/ioport.h>
 
 #define GIC_MAX_INTRS			256
 
@@ -245,6 +246,8 @@
 #define GIC_SHARED_TO_HWIRQ(x)	(GIC_SHARED_HWIRQ_BASE + (x))
 #define GIC_HWIRQ_TO_SHARED(x)	((x) - GIC_SHARED_HWIRQ_BASE)
 
+#ifdef CONFIG_MIPS_GIC
+
 extern unsigned int gic_present;
 
 extern void gic_init(unsigned long gic_base_addr,
@@ -264,4 +267,18 @@ extern unsigned int plat_ipi_resched_int_xlate(unsigned int);
 extern int gic_get_c0_compare_int(void);
 extern int gic_get_c0_perfcount_int(void);
 extern int gic_get_c0_fdc_int(void);
+extern int gic_get_usm_range(struct resource *gic_usm_res);
+
+#else /* CONFIG_MIPS_GIC */
+
+#define gic_present	0
+
+static int gic_get_usm_range(struct resource *gic_usm_res)
+{
+	/* Shouldn't be called. */
+	return -1
+}
+
+#endif /* CONFIG_MIPS_GIC */
+
 #endif /* __LINUX_IRQCHIP_MIPS_GIC_H */
-- 
2.6.1

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#1244553 — Re: [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section

On 12/10/15 10:40, Markos Chandras wrote:
> From: Alex Smith <alex.smith@imgtec.com>
> 
> The GIC provides a "user-mode visible" section containing a mirror of
> the counter registers which can be mapped into user memory. This will
> be used by the VDSO time function implementations, so provide a
> function to map it in.
> 
> When the GIC is not enabled in Kconfig a dummy inline version of this
> function is provided, along with "#define gic_present 0", so that we
> don't have to litter the VDSO code with ifdefs.
> 
> [markos.chandras@imgtec.com:
> - Move mapping code to arch/mips/kernel/vdso.c and use a resource
> type to get the GIC usermode information
> - Avoid renaming function arguments and use __gic_base_addr to hold
> the base GIC address prior to ioremap.]
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Jason Cooper <jason@lakedaemon.net>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Alex Smith <alex.smith@imgtec.com>
> Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
> ---
> Changes since v1:
> - Move mapping code to arch/mips/kernel/vdso.c and use a resource
> type to get the GIC usermode information
> - Avoid renaming function arguments and use __gic_base_addr to hold
> the base GIC address prior to ioremap.
> 
> http://www.linux-mips.org/archives/linux-mips/2015-09/msg00316.html
> ---
>  drivers/irqchip/irq-mips-gic.c   | 14 ++++++++++++++
>  include/linux/irqchip/mips-gic.h | 17 +++++++++++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
> index af2f16bb8a94..392beebb81ee 100644
> --- a/drivers/irqchip/irq-mips-gic.c
> +++ b/drivers/irqchip/irq-mips-gic.c
> @@ -29,6 +29,7 @@ struct gic_pcpu_mask {
>  	DECLARE_BITMAP(pcpu_mask, GIC_MAX_INTRS);
>  };
>  
> +static unsigned long __gic_base_addr;
>  static void __iomem *gic_base;
>  static struct gic_pcpu_mask pcpu_masks[NR_CPUS];
>  static DEFINE_SPINLOCK(gic_lock);
> @@ -301,6 +302,17 @@ int gic_get_c0_fdc_int(void)
>  				  GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_FDC));
>  }
>  
> +int gic_get_usm_range(struct resource *gic_usm_res)
> +{
> +	if (!gic_present)
> +		return -1;
> +
> +	gic_usm_res->start = __gic_base_addr + USM_VISIBLE_SECTION_OFS;
> +	gic_usm_res->end = gic_usm_res->start + (USM_VISIBLE_SECTION_SIZE - 1);
> +
> +	return 0;
> +}
> +
>  static void gic_handle_shared_int(bool chained)
>  {
>  	unsigned int i, intr, virq, gic_reg_step = mips_cm_is64 ? 8 : 4;
> @@ -790,6 +802,8 @@ static void __init __gic_init(unsigned long gic_base_addr,
>  {
>  	unsigned int gicconfig;
>  
> +	__gic_base_addr = gic_base_addr;
> +
>  	gic_base = ioremap_nocache(gic_base_addr, gic_addrspace_size);
>  
>  	gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG));
> diff --git a/include/linux/irqchip/mips-gic.h b/include/linux/irqchip/mips-gic.h
> index 4e6861605050..71ab7c548550 100644
> --- a/include/linux/irqchip/mips-gic.h
> +++ b/include/linux/irqchip/mips-gic.h
> @@ -9,6 +9,7 @@
>  #define __LINUX_IRQCHIP_MIPS_GIC_H
>  
>  #include <linux/clocksource.h>
> +#include <linux/ioport.h>
>  
>  #define GIC_MAX_INTRS			256
>  
> @@ -245,6 +246,8 @@
>  #define GIC_SHARED_TO_HWIRQ(x)	(GIC_SHARED_HWIRQ_BASE + (x))
>  #define GIC_HWIRQ_TO_SHARED(x)	((x) - GIC_SHARED_HWIRQ_BASE)
>  
> +#ifdef CONFIG_MIPS_GIC
> +
>  extern unsigned int gic_present;
>  
>  extern void gic_init(unsigned long gic_base_addr,
> @@ -264,4 +267,18 @@ extern unsigned int plat_ipi_resched_int_xlate(unsigned int);
>  extern int gic_get_c0_compare_int(void);
>  extern int gic_get_c0_perfcount_int(void);
>  extern int gic_get_c0_fdc_int(void);
> +extern int gic_get_usm_range(struct resource *gic_usm_res);
> +
> +#else /* CONFIG_MIPS_GIC */
> +
> +#define gic_present	0
> +
> +static int gic_get_usm_range(struct resource *gic_usm_res)
> +{
> +	/* Shouldn't be called. */
> +	return -1
> +}
> +
> +#endif /* CONFIG_MIPS_GIC */
> +
>  #endif /* __LINUX_IRQCHIP_MIPS_GIC_H */
> 

This looks much better than the previous version (though I cannot find
the two other patches on LKML just yet).

FWIW:

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...
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#1244566 — Re: [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section

On Mon, 12 Oct 2015, Marc Zyngier wrote:
> On 12/10/15 10:40, Markos Chandras wrote:
> > From: Alex Smith <alex.smith@imgtec.com>
> > 
> > The GIC provides a "user-mode visible" section containing a mirror of
> > the counter registers which can be mapped into user memory. This will
> > be used by the VDSO time function implementations, so provide a
> > function to map it in.

<SNIP>
 
> 
> This looks much better than the previous version (though I cannot find
> the two other patches on LKML just yet).

Yes, it looks better. But I really have to ask the question why we are
trying to pack the world and somemore into an irq chip driver. We
already have the completely misplaced gic_read_count() there.

While I understand that all of this is in the GIC block at least
according to the documentation, technically it's different hardware
blocks. And logically its different as well.

So why not describe the various blocks (interrupt controller, timer,
shadow timer) as separate entities in the device tree and let each
subsystem look them up on their own. This cross subsystem hackery is
just horrible and does not buy anything except merge dependencies and
other avoidable hassle.

Thoughts?

Thanks,

	tglx


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#1247621 — Re: [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section

On 10/12/2015 11:16 AM, Thomas Gleixner wrote:
> On Mon, 12 Oct 2015, Marc Zyngier wrote:
>> On 12/10/15 10:40, Markos Chandras wrote:
>>> From: Alex Smith <alex.smith@imgtec.com>
>>>
>>> The GIC provides a "user-mode visible" section containing a mirror of
>>> the counter registers which can be mapped into user memory. This will
>>> be used by the VDSO time function implementations, so provide a
>>> function to map it in.
> <SNIP>
>   
>> This looks much better than the previous version (though I cannot find
>> the two other patches on LKML just yet).
> Yes, it looks better. But I really have to ask the question why we are
> trying to pack the world and somemore into an irq chip driver. We
> already have the completely misplaced gic_read_count() there.

This code has a bad history. It was scattered all over the place in arch 
code. Andrew Bresticker did a good job cleaning it up and moved it to 
this irqchip driver.

     https://lkml.org/lkml/2014/9/18/487
     https://lkml.org/lkml/2014/10/20/481

>
> While I understand that all of this is in the GIC block at least
> according to the documentation, technically it's different hardware
> blocks. And logically its different as well.

Yes but they're exposed through the same register interface.

>
> So why not describe the various blocks (interrupt controller, timer,
> shadow timer) as separate entities in the device tree and let each
> subsystem look them up on their own. This cross subsystem hackery is
> just horrible and does not buy anything except merge dependencies and
> other avoidable hassle.

There's a mips-gic-timer driver in drivers/clocksource. But in device 
tree it's a subnode of the irqchip driver.

http://lxr.free-electrons.com/source/drivers/clocksource/mips-gic-timer.c
http://lxr.free-electrons.com/source/Documentation/devicetree/bindings/interrupt-controller/mips-gic.txt

>
> Thoughts?
>

It could be refactored but the DT binding already specifies the GIC 
timer as a subnode of GIC. Exposing this usermode register is the only 
thing left in the register set that GIC driver wasn't dealing with.

Little gain in changing all of this now I think?

Thanks,
Qais
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#1247637 — Re: [PATCH v2 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section

On Thu, 15 Oct 2015, Qais Yousef wrote:
> It could be refactored but the DT binding already specifies the GIC timer as a
> subnode of GIC. Exposing this usermode register is the only thing left in the
> register set that GIC driver wasn't dealing with.
> 
> Little gain in changing all of this now I think?

Well, the not so little gain is clear separation and a sane design.

Thanks,

	tglx
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