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authorRandy Vinson <rvinson@mvista.com>2007-06-06 16:26:15 -0700
committerKumar Gala <galak@kernel.crashing.org>2007-07-23 22:34:40 -0500
commit3620fc1da28ad32d10d7c83eab33f48ec5b1da54 (patch)
treeea8fd966c21a23db7e5d2400f89587d7ff137bf3
parenteb12af43333dd9d54158f35147a79628c41152db (diff)
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[POWERPC] 85xxCDS: Allow 8259 cascade to share an MPIC interrupt line.
The Freescale MPC8555CDS and MPC8548CDS reference hardware has a legacy 8259 interrupt controller pair contained within a VIA VT82C686B Southbridge on the main carrier board. The processor complex plugs into the carrier card using a PCI slot which limits the available interrupts to the INTA-INTD PCI interrupts. The output of the 8259 cascade pair is routed through a gate array and connected to the PCI INTA interrupt line. The normal interrupt chaining hook (set_irq_chained_handler) does not allow sharing of the chained interrupt which prevents the use of PCI INTA by PCI devices. This patch allows the 8259 cascade pair to share their interrupt line with PCI devices. NOTE: The addition of the .end routine for the MPIC is not strictly necessary for this patch. It's there so this code will run from within the threaded interrupt context used by the Real Time patch. Signed-off-by: Randy Vinson <rvinson@mvista.com> Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
-rw-r--r--arch/powerpc/platforms/85xx/Kconfig1
-rw-r--r--arch/powerpc/platforms/85xx/mpc85xx_cds.c37
2 files changed, 32 insertions, 6 deletions
diff --git a/arch/powerpc/platforms/85xx/Kconfig b/arch/powerpc/platforms/85xx/Kconfig
index 99bb74da0760..f58184086c8c 100644
--- a/arch/powerpc/platforms/85xx/Kconfig
+++ b/arch/powerpc/platforms/85xx/Kconfig
@@ -18,6 +18,7 @@ config MPC8560_ADS
config MPC85xx_CDS
bool "Freescale MPC85xx CDS"
select DEFAULT_UIMAGE
+ select PPC_I8259
help
This option enables support for the MPC85xx CDS board
diff --git a/arch/powerpc/platforms/85xx/mpc85xx_cds.c b/arch/powerpc/platforms/85xx/mpc85xx_cds.c
index 71200bdce05a..81b70628df75 100644
--- a/arch/powerpc/platforms/85xx/mpc85xx_cds.c
+++ b/arch/powerpc/platforms/85xx/mpc85xx_cds.c
@@ -24,6 +24,7 @@
#include <linux/seq_file.h>
#include <linux/initrd.h>
#include <linux/module.h>
+#include <linux/interrupt.h>
#include <linux/fsl_devices.h>
#include <asm/system.h>
@@ -119,16 +120,30 @@ DECLARE_PCI_FIXUP_EARLY(0x3fff, 0x1957, skip_fake_bridge);
DECLARE_PCI_FIXUP_EARLY(0xff3f, 0x5719, skip_fake_bridge);
#ifdef CONFIG_PPC_I8259
-#warning The i8259 PIC support is currently broken
-static void mpc85xx_8259_cascade(unsigned int irq, struct irq_desc *desc)
+static void mpc85xx_8259_cascade_handler(unsigned int irq,
+ struct irq_desc *desc)
{
unsigned int cascade_irq = i8259_irq();
if (cascade_irq != NO_IRQ)
+ /* handle an interrupt from the 8259 */
generic_handle_irq(cascade_irq);
- desc->chip->eoi(irq);
+ /* check for any interrupts from the shared IRQ line */
+ handle_fasteoi_irq(irq, desc);
}
+
+static irqreturn_t mpc85xx_8259_cascade_action(int irq, void *dev_id)
+{
+ return IRQ_HANDLED;
+}
+
+static struct irqaction mpc85xxcds_8259_irqaction = {
+ .handler = mpc85xx_8259_cascade_action,
+ .flags = IRQF_SHARED,
+ .mask = CPU_MASK_NONE,
+ .name = "8259 cascade",
+};
#endif /* PPC_I8259 */
#endif /* CONFIG_PCI */
@@ -137,7 +152,7 @@ static void __init mpc85xx_cds_pic_init(void)
struct mpic *mpic;
struct resource r;
struct device_node *np = NULL;
-#ifdef CONFIG_PPC_I8259
+#if defined(CONFIG_PPC_I8259) && defined(CONFIG_PCI)
struct device_node *cascade_node = NULL;
int cascade_irq;
#endif
@@ -165,7 +180,7 @@ static void __init mpc85xx_cds_pic_init(void)
mpic_init(mpic);
-#ifdef CONFIG_PPC_I8259
+#if defined(CONFIG_PPC_I8259) && defined(CONFIG_PCI)
/* Initialize the i8259 controller */
for_each_node_by_type(np, "interrupt-controller")
if (of_device_is_compatible(np, "chrp,iic")) {
@@ -187,7 +202,17 @@ static void __init mpc85xx_cds_pic_init(void)
i8259_init(cascade_node, 0);
of_node_put(cascade_node);
- set_irq_chained_handler(cascade_irq, mpc85xx_8259_cascade);
+ /*
+ * Hook the interrupt to make sure desc->action is never NULL.
+ * This is required to ensure that the interrupt does not get
+ * disabled when the last user of the shared IRQ line frees their
+ * interrupt.
+ */
+ if (setup_irq(cascade_irq, &mpc85xxcds_8259_irqaction))
+ printk(KERN_ERR "Failed to setup cascade interrupt\n");
+ else
+ /* Success. Connect our low-level cascade handler. */
+ set_irq_handler(cascade_irq, mpc85xx_8259_cascade_handler);
#endif /* CONFIG_PPC_I8259 */
}
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