ARM: imx6: convert GPC to stacked domains

IMX6 has been (ab)using the gic_arch_extn to provide
wakeup from suspend, and it makes a lot of sense to convert
this code to use stacked domains instead.

This patch does just this, updating the DT files to actually
reflect what the HW provides.

BIG FAT WARNING: because the DTs were so far lying by not
exposing the fact that the GPC block is actually the first
interrupt controller in the chain, kernels with this patch
applied wont have any suspend-resume facility when booted
with old DTs, and old kernels with updated DTs won't even boot.

Tested-by: Stefan Agner <stefan@agner.ch>
Acked-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

1 files changed, 103 insertions, 24 deletions

diff --git a/arch/arm/mach-imx/gpc.c b/arch/arm/mach-imx/gpc.c
index 029f59ce2712..6f1f77ed0c71 100644
--- a/arch/arm/mach-imx/gpc.c
+++ b/arch/arm/mach-imx/gpc.c
@@ -36,6 +36,7 @@
 #define GPC_PGC_SW_SHIFT        0x0
 
 #define IMR_NUM                 4
+#define GPC_MAX_IRQS            (IMR_NUM * 32)
 
 #define GPU_VPU_PUP_REQ         BIT(1)
 #define GPU_VPU_PDN_REQ         BIT(0)
@@ -99,17 +100,17 @@ void imx_gpc_post_resume(void)
 
 static int imx_gpc_irq_set_wake(struct irq_data *d, unsigned int on)
 {
-        unsigned int idx = d->hwirq / 32 - 1;
+        unsigned int idx = d->hwirq / 32;
         u32 mask;
 
-        /* Sanity check for SPI irq */
-        if (d->hwirq < 32)
-                return -EINVAL;
-
         mask = 1 << d->hwirq % 32;
         gpc_wake_irqs[idx] = on ? gpc_wake_irqs[idx] | mask :
                                   gpc_wake_irqs[idx] & ~mask;
 
+        /*
+         * Do *not* call into the parent, as the GIC doesn't have any
+         * wake-up facility...
+         */
         return 0;
 }
 
@@ -139,7 +140,7 @@ void imx_gpc_hwirq_unmask(unsigned int hwirq)
         void __iomem *reg;
         u32 val;
 
-        reg = gpc_base + GPC_IMR1 + (hwirq / 32 - 1) * 4;
+        reg = gpc_base + GPC_IMR1 + hwirq / 32 * 4;
         val = readl_relaxed(reg);
         val &= ~(1 << hwirq % 32);
         writel_relaxed(val, reg);
@@ -150,7 +151,7 @@ void imx_gpc_hwirq_mask(unsigned int hwirq)
         void __iomem *reg;
         u32 val;
 
-        reg = gpc_base + GPC_IMR1 + (hwirq / 32 - 1) * 4;
+        reg = gpc_base + GPC_IMR1 + hwirq / 32 * 4;
         val = readl_relaxed(reg);
         val |= 1 << (hwirq % 32);
         writel_relaxed(val, reg);
@@ -158,41 +159,119 @@ void imx_gpc_hwirq_mask(unsigned int hwirq)
 
 static void imx_gpc_irq_unmask(struct irq_data *d)
 {
-        /* Sanity check for SPI irq */
-        if (d->hwirq < 32)
-                return;
-
         imx_gpc_hwirq_unmask(d->hwirq);
+        irq_chip_unmask_parent(d);
 }
 
 static void imx_gpc_irq_mask(struct irq_data *d)
 {
-        /* Sanity check for SPI irq */
-        if (d->hwirq < 32)
-                return;
-
         imx_gpc_hwirq_mask(d->hwirq);
+        irq_chip_mask_parent(d);
 }
 
-void __init imx_gpc_init(void)
+static struct irq_chip imx_gpc_chip = {
+        .name           = "GPC",
+        .irq_eoi        = irq_chip_eoi_parent,
+        .irq_mask       = imx_gpc_irq_mask,
+        .irq_unmask     = imx_gpc_irq_unmask,
+        .irq_retrigger  = irq_chip_retrigger_hierarchy,
+        .irq_set_wake   = imx_gpc_irq_set_wake,
+};
+
+static int imx_gpc_domain_xlate(struct irq_domain *domain,
+                                struct device_node *controller,
+                                const u32 *intspec,
+                                unsigned int intsize,
+                                unsigned long *out_hwirq,
+                                unsigned int *out_type)
 {
-        struct device_node *np;
+        if (domain->of_node != controller)
+                return -EINVAL; /* Shouldn't happen, really... */
+        if (intsize != 3)
+                return -EINVAL; /* Not GIC compliant */
+        if (intspec[0] != 0)
+                return -EINVAL; /* No PPI should point to this domain */
+
+        *out_hwirq = intspec[1];
+        *out_type = intspec[2];
+        return 0;
+}
+
+static int imx_gpc_domain_alloc(struct irq_domain *domain,
+                                  unsigned int irq,
+                                  unsigned int nr_irqs, void *data)
+{
+        struct of_phandle_args *args = data;
+        struct of_phandle_args parent_args;
+        irq_hw_number_t hwirq;
         int i;
 
-        np = of_find_compatible_node(NULL, NULL, "fsl,imx6q-gpc");
-        gpc_base = of_iomap(np, 0);
-        WARN_ON(!gpc_base);
+        if (args->args_count != 3)
+                return -EINVAL; /* Not GIC compliant */
+        if (args->args[0] != 0)
+                return -EINVAL; /* No PPI should point to this domain */
+
+        hwirq = args->args[1];
+        if (hwirq >= GPC_MAX_IRQS)
+                return -EINVAL; /* Can't deal with this */
+
+        for (i = 0; i < nr_irqs; i++)
+                irq_domain_set_hwirq_and_chip(domain, irq + i, hwirq + i,
+                                              &imx_gpc_chip, NULL);
+
+        parent_args = *args;
+        parent_args.np = domain->parent->of_node;
+        return irq_domain_alloc_irqs_parent(domain, irq, nr_irqs, &parent_args);
+}
+
+static struct irq_domain_ops imx_gpc_domain_ops = {
+        .xlate  = imx_gpc_domain_xlate,
+        .alloc  = imx_gpc_domain_alloc,
+        .free   = irq_domain_free_irqs_common,
+};
+
+static int __init imx_gpc_init(struct device_node *node,
+                               struct device_node *parent)
+{
+        struct irq_domain *parent_domain, *domain;
+        int i;
+
+        if (!parent) {
+                pr_err("%s: no parent, giving up\n", node->full_name);
+                return -ENODEV;
+        }
+
+        parent_domain = irq_find_host(parent);
+        if (!parent_domain) {
+                pr_err("%s: unable to obtain parent domain\n", node->full_name);
+                return -ENXIO;
+        }
+
+        gpc_base = of_iomap(node, 0);
+        if (WARN_ON(!gpc_base))
+                return -ENOMEM;
+
+        domain = irq_domain_add_hierarchy(parent_domain, 0, GPC_MAX_IRQS,
+                                          node, &imx_gpc_domain_ops,
+                                          NULL);
+        if (!domain) {
+                iounmap(gpc_base);
+                return -ENOMEM;
+        }
 
         /* Initially mask all interrupts */
         for (i = 0; i < IMR_NUM; i++)
                 writel_relaxed(~0, gpc_base + GPC_IMR1 + i * 4);
 
-        /* Register GPC as the secondary interrupt controller behind GIC */
-        gic_arch_extn.irq_mask = imx_gpc_irq_mask;
-        gic_arch_extn.irq_unmask = imx_gpc_irq_unmask;
-        gic_arch_extn.irq_set_wake = imx_gpc_irq_set_wake;
+        return 0;
 }
 
+/*
+ * We cannot use the IRQCHIP_DECLARE macro that lives in
+ * drivers/irqchip, so we're forced to roll our own. Not very nice.
+ */
+OF_DECLARE_2(irqchip, imx_gpc, "fsl,imx6q-gpc", imx_gpc_init);
+
 #ifdef CONFIG_PM_GENERIC_DOMAINS
 
 static void _imx6q_pm_pu_power_off(struct generic_pm_domain *genpd)