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SubjectRe: [PATCH v2 02/10] irqchip: add irqchip driver for nuc900
Hi Wan Zongshun,

On Thu, Jul 14, 2016 at 11:36:53AM +0800, Wan Zongshun wrote:
> On 2016年07月14日 04:09, Jason Cooper wrote:
> >On Sun, Jul 10, 2016 at 03:27:22PM +0800, Wan Zongshun wrote:
> >>This patch is to add irqchip driver support for nuc900 plat,
> >>current this driver only supports nuc970 SoC.
> >>
> >>Signed-off-by: Wan Zongshun <mcuos.com@gmail.com>
> >>---
> >> arch/arm/mach-w90x900/include/mach/irqs.h | 5 +
> >> drivers/irqchip/Makefile | 1 +
> >> drivers/irqchip/irq-nuc900.c | 150 ++++++++++++++++++++++++++++++
> >> 3 files changed, 156 insertions(+)
> >> create mode 100644 drivers/irqchip/irq-nuc900.c
> >>
> >>diff --git a/arch/arm/mach-w90x900/include/mach/irqs.h b/arch/arm/mach-w90x900/include/mach/irqs.h
> >>index 9d5cba3..3b035c6 100644
> >>--- a/arch/arm/mach-w90x900/include/mach/irqs.h
> >>+++ b/arch/arm/mach-w90x900/include/mach/irqs.h
> >>@@ -59,7 +59,12 @@
> >> #define IRQ_KPI W90X900_IRQ(29)
> >> #define IRQ_P2SGROUP W90X900_IRQ(30)
> >> #define IRQ_ADC W90X900_IRQ(31)
> >>+
> >>+#if !defined(CONFIG_SOC_NUC900)
> >> #define NR_IRQS (IRQ_ADC+1)
> >>+#else
> >>+#define NR_IRQS 62
> >>+#endif
> >
> >Arnd already covered this...
> >
> >>
> >> /*for irq group*/
> >>
> >>diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> >>index 38853a1..9ccd5af8a 100644
> >>--- a/drivers/irqchip/Makefile
> >>+++ b/drivers/irqchip/Makefile
> >>@@ -69,3 +69,4 @@ obj-$(CONFIG_PIC32_EVIC) += irq-pic32-evic.o
> >> obj-$(CONFIG_MVEBU_ODMI) += irq-mvebu-odmi.o
> >> obj-$(CONFIG_LS_SCFG_MSI) += irq-ls-scfg-msi.o
> >> obj-$(CONFIG_EZNPS_GIC) += irq-eznps.o
> >>+obj-$(CONFIG_SOC_NUC970) += irq-nuc900.o
> >>diff --git a/drivers/irqchip/irq-nuc900.c b/drivers/irqchip/irq-nuc900.c
> >>new file mode 100644
> >>index 0000000..c4b2e39
> >>--- /dev/null
> >>+++ b/drivers/irqchip/irq-nuc900.c
> >>@@ -0,0 +1,150 @@
> >>+/*
> >>+ * Copyright 2016 Wan Zongshun <mcuos.com@gmail.com>
> >>+ *
> >>+ * The code contained herein is licensed under the GNU General Public
> >>+ * License. You may obtain a copy of the GNU General Public License
> >>+ * Version 2 or later at the following locations:
> >>+ *
> >>+ * http://www.opensource.org/licenses/gpl-license.html
> >>+ * http://www.gnu.org/copyleft/gpl.html
> >>+ */
> >>+
> >>+#include <linux/module.h>
> >>+#include <linux/init.h>
> >>+#include <linux/irq.h>
> >>+#include <linux/irqchip.h>
> >>+#include <linux/irqdomain.h>
> >>+#include <linux/io.h>
> >>+#include <linux/ioport.h>
> >>+#include <linux/of_address.h>
> >>+#include <linux/of_irq.h>
> >>+
> >>+#include <asm/exception.h>
> >>+#include <asm/hardirq.h>
> >>+
> >>+#define REG_AIC_SCR1 0x00
> >>+#define REG_AIC_SCR2 0x04
> >>+#define REG_AIC_SCR3 0x08
> >>+#define REG_AIC_SCR4 0x0C
> >>+#define REG_AIC_SCR5 0x10
> >>+#define REG_AIC_SCR6 0x14
> >>+#define REG_AIC_SCR7 0x18
> >>+#define REG_AIC_SCR8 0x1C
> >>+#define REG_AIC_SCR9 0x20
> >>+#define REG_AIC_SCR10 0x24
> >>+#define REG_AIC_SCR11 0x28
> >>+#define REG_AIC_SCR12 0x2C
> >>+#define REG_AIC_SCR13 0x30
> >>+#define REG_AIC_SCR14 0x34
> >>+#define REG_AIC_SCR15 0x38
> >>+#define REG_AIC_IRSR 0x100
> >>+#define REG_AIC_IRSRH 0x104
> >>+#define REG_AIC_IASR 0x108
> >>+#define REG_AIC_IASRH 0x10C
> >>+#define REG_AIC_ISR 0x110
> >>+#define REG_AIC_ISRH 0x114
> >>+#define REG_AIC_IPER 0x118
> >>+#define REG_AIC_ISNR 0x120
> >>+#define REG_AIC_OISR 0x124
> >>+#define REG_AIC_IMR 0x128
> >>+#define REG_AIC_IMRH 0x12C
> >>+#define REG_AIC_MECR 0x130
> >>+#define REG_AIC_MECRH 0x134
> >>+#define REG_AIC_MDCR 0x138
> >>+#define REG_AIC_MDCRH 0x13C
> >>+#define REG_AIC_SSCR 0x140
> >>+#define REG_AIC_SSCRH 0x144
> >>+#define REG_AIC_SCCR 0x148
> >>+#define REG_AIC_SCCRH 0x14C
> >>+#define REG_AIC_EOSCR 0x150
> >
> >Please remove unused defines.
>
> Okay.
>
> >
> >>+
> >>+static void __iomem *aic_base;
> >>+static struct irq_domain *aic_domain;
> >>+
> >>+static void nuc900_irq_mask(struct irq_data *d)
> >>+{
> >>+ if (d->irq < 32)
> >>+ writel(1 << (d->irq), aic_base + REG_AIC_MDCR);
> >>+ else
> >>+ writel(1 << (d->irq - 32), aic_base + REG_AIC_MDCRH);
> >>+}
> >>+
> >>+static void nuc900_irq_ack(struct irq_data *d)
> >>+{
> >>+ writel(0x01, aic_base + REG_AIC_EOSCR);
> >>+}
> >>+
> >>+static void nuc900_irq_unmask(struct irq_data *d)
> >>+{
> >>+ if (d->irq < 32)
> >>+ writel(1 << (d->irq), aic_base + REG_AIC_MECR);
> >>+ else
> >>+ writel(1 << (d->irq - 32), aic_base + REG_AIC_MECRH);
> >>+}
> >>+
> >>+static struct irq_chip nuc900_irq_chip = {
> >>+ .irq_ack = nuc900_irq_ack,
> >>+ .irq_mask = nuc900_irq_mask,
> >>+ .irq_unmask = nuc900_irq_unmask,
> >>+};
> >>+
> >>+void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
> >>+{
> >>+ u32 hwirq;
> >>+
> >>+ hwirq = readl(aic_base + REG_AIC_IPER);
> >>+ hwirq = readl(aic_base + REG_AIC_ISNR);
> >>+ if (!hwirq)
> >>+ writel(0x01, aic_base + REG_AIC_EOSCR);
> >
> >Could you explain what's going on here?
>
> AIC_IPER, When the AIC generates the interrupt, VECTOR represents
> the interrupt channel number that is active, enabled, and has the
> highest priority.
>
> The value of VECTOR is copied to the register AIC_ISNR thereafter by
> the AIC. This register was restored a value 0 after it was read by
> the
> interrupt handler.

So, iiuc, the first readl() of AIC_IPER kicks the AIC to copy the value
of VECTOR into AIC_ISNR? Then we can read it?

If so, please add a comment above the code explaining that.

> So I must read two registers for one irq number, after read IPER,
> the ISNR(bit0:5) will be updated. ISNR value has no need do offset,
> it is better than read IPER(bit2:7).

But you aren't using the value from the first readl(...AIC_IPER)? You
overwrite hwirq with the value from the second readl(...AIC_ISNR)
...

The first part of your explaination makes sense, but this part isn't
clear to me.


> “writel(0x01, aic_base + REG_AIC_EOSCR);” seems not necessary here,
> since irqchip has the ack interface. I will remove it.

Ok, thanks.

> This AIC_EOSCR register is used by the interrupt service routine to
> indicate that it is completely served. Thus, the
> interrupt handler can write any value to this register to indicate
> the end of its interrupt service.

A short comment in the ack routine would be helpful.


> >>+IRQCHIP_DECLARE(nuc900, "nuvoton,nuc900-aic", aic_of_init);
> >
> >afaict, there is no 'nuc900', that's a family. If so, this compatible
> >needs to be 'nuvoton,nuc970-aic'.
> >
>
> IRQCHIP_DECLARE(nuvoton, "nuvoton,nuc900-aic", aic_of_init);, change
> nuc900 to nuvoton, ok?

No, I was only talking about the second argument. The compatible
string. For devicetree, it needs to refer to a specific model number.
I suspect 'nuc900' is equivalent to saying 'nuc9xx'. Meaning it refers
to a family of devices. The compatible string needs to refer
specifically to the first model that the binding is compatible with. In
this case, I presume that would be 'nuvoton,nuc970-aic'.

thx,

Jason.

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