SPARC/LEON: power down instruction different of different LEONs

The way a LEON is powered down is implemented differently depending
on CHIP type. The AMBA Plug&Play system ID tells revision of GRLIB
and CHIP.

This is for example needed by the GR-LEON4-ITX board and the UT699.

Previously the power down support for LEON was limited to SMP, now
both SMP and UP systems use the instruction.

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/leon_pmc.c

@@ -0,0 +1,82 @@
+/* leon_pmc.c: LEON Power-down cpu_idle() handler
+ *
+ * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) Aeroflex Gaisler AB
+ */
+
+#include <linux/init.h>
+#include <linux/pm.h>
+
+#include <asm/leon_amba.h>
+#include <asm/leon.h>
+
+/* List of Systems that need fixup instructions around power-down instruction */
+unsigned int pmc_leon_fixup_ids[] = {
+	AEROFLEX_UT699,
+	GAISLER_GR712RC,
+	LEON4_NEXTREME1,
+	0
+};
+
+int pmc_leon_need_fixup(void)
+{
+	unsigned int systemid = amba_system_id >> 16;
+	unsigned int *id;
+
+	id = &pmc_leon_fixup_ids[0];
+	while (*id != 0) {
+		if (*id == systemid)
+			return 1;
+		id++;
+	}
+
+	return 0;
+}
+
+/*
+ * CPU idle callback function for systems that need some extra handling
+ * See .../arch/sparc/kernel/process.c
+ */
+void pmc_leon_idle_fixup(void)
+{
+	/* Prepare an address to a non-cachable region. APB is always
+	 * none-cachable. One instruction is executed after the Sleep
+	 * instruction, we make sure to read the bus and throw away the
+	 * value by accessing a non-cachable area, also we make sure the
+	 * MMU does not get a TLB miss here by using the MMU BYPASS ASI.
+	 */
+	register unsigned int address = (unsigned int)leon3_irqctrl_regs;
+	__asm__ __volatile__ (
+		"mov	%%g0, %%asr19\n"
+		"lda	[%0] %1, %%g0\n"
+		:
+		: "r"(address), "i"(ASI_LEON_BYPASS));
+}
+
+/*
+ * CPU idle callback function
+ * See .../arch/sparc/kernel/process.c
+ */
+void pmc_leon_idle(void)
+{
+	/* For systems without power-down, this will be no-op */
+	__asm__ __volatile__ ("mov	%g0, %asr19\n\t");
+}
+
+/* Install LEON Power Down function */
+static int __init leon_pmc_install(void)
+{
+	/* Assign power management IDLE handler */
+	if (pmc_leon_need_fixup())
+		pm_idle = pmc_leon_idle_fixup;
+	else
+		pm_idle = pmc_leon_idle;
+
+	printk(KERN_INFO "leon: power management initialized\n");
+
+	return 0;
+}
+
+/* This driver is not critical to the boot process, don't care
+ * if initialized late.
+ */
+late_initcall(leon_pmc_install);