m68knommu: add basic mmu-less m548x support

Add a very basic mmu-less support for coldfire m548x family.  This is perhaps
also valid for m547x family.  The port comprises the serial, tick timer and
reboot support.  The gpio part compiles but is empty.  This gives a functional
albeit limited linux for the m548x coldfire family.  This has been tested
on a Freescale M548xEVB Lite board with a M5484 processor and the default
dbug monitor.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>

1 files changed, 145 insertions, 0 deletions

diff --git a/arch/m68knommu/platform/coldfire/sltimers.c b/arch/m68knommu/platform/coldfire/sltimers.c
new file mode 100644
index 00000000000..0a1b937c3e1
--- /dev/null
+++ b/arch/m68knommu/platform/coldfire/sltimers.c
@@ -0,0 +1,145 @@
+/***************************************************************************/
+
+/*
+ *	sltimers.c -- generic ColdFire slice timer support.
+ *
+ *	Copyright (C) 2009-2010, Philippe De Muyter <phdm@macqel.be>
+ *	based on
+ *	timers.c -- generic ColdFire hardware timer support.
+ *	Copyright (C) 1999-2008, Greg Ungerer <gerg@snapgear.com>
+ */
+
+/***************************************************************************/
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/profile.h>
+#include <linux/clocksource.h>
+#include <asm/io.h>
+#include <asm/traps.h>
+#include <asm/machdep.h>
+#include <asm/coldfire.h>
+#include <asm/mcfslt.h>
+#include <asm/mcfsim.h>
+
+/***************************************************************************/
+
+#ifdef CONFIG_HIGHPROFILE
+
+/*
+ *	By default use Slice Timer 1 as the profiler clock timer.
+ */
+#define	PA(a)	(MCF_MBAR + MCFSLT_TIMER1 + (a))
+
+/*
+ *	Choose a reasonably fast profile timer. Make it an odd value to
+ *	try and get good coverage of kernel operations.
+ */
+#define	PROFILEHZ	1013
+
+irqreturn_t mcfslt_profile_tick(int irq, void *dummy)
+{
+	/* Reset Slice Timer 1 */
+	__raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, PA(MCFSLT_SSR));
+	if (current->pid)
+		profile_tick(CPU_PROFILING);
+	return IRQ_HANDLED;
+}
+
+static struct irqaction mcfslt_profile_irq = {
+	.name	 = "profile timer",
+	.flags	 = IRQF_DISABLED | IRQF_TIMER,
+	.handler = mcfslt_profile_tick,
+};
+
+void mcfslt_profile_init(void)
+{
+	printk(KERN_INFO "PROFILE: lodging TIMER 1 @ %dHz as profile timer\n",
+	       PROFILEHZ);
+
+	setup_irq(MCF_IRQ_PROFILER, &mcfslt_profile_irq);
+
+	/* Set up TIMER 2 as high speed profile clock */
+	__raw_writel(MCF_BUSCLK / PROFILEHZ - 1, PA(MCFSLT_STCNT));
+	__raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
+								PA(MCFSLT_SCR));
+
+}
+
+#endif	/* CONFIG_HIGHPROFILE */
+
+/***************************************************************************/
+
+/*
+ *	By default use Slice Timer 0 as the system clock timer.
+ */
+#define	TA(a)	(MCF_MBAR + MCFSLT_TIMER0 + (a))
+
+static u32 mcfslt_cycles_per_jiffy;
+static u32 mcfslt_cnt;
+
+static irqreturn_t mcfslt_tick(int irq, void *dummy)
+{
+	/* Reset Slice Timer 0 */
+	__raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, TA(MCFSLT_SSR));
+	mcfslt_cnt += mcfslt_cycles_per_jiffy;
+	return arch_timer_interrupt(irq, dummy);
+}
+
+static struct irqaction mcfslt_timer_irq = {
+	.name	 = "timer",
+	.flags	 = IRQF_DISABLED | IRQF_TIMER,
+	.handler = mcfslt_tick,
+};
+
+static cycle_t mcfslt_read_clk(struct clocksource *cs)
+{
+	unsigned long flags;
+	u32 cycles;
+	u16 scnt;
+
+	local_irq_save(flags);
+	scnt = __raw_readl(TA(MCFSLT_SCNT));
+	cycles = mcfslt_cnt;
+	local_irq_restore(flags);
+
+	/* substract because slice timers count down */
+	return cycles - scnt;
+}
+
+static struct clocksource mcfslt_clk = {
+	.name	= "slt",
+	.rating	= 250,
+	.read	= mcfslt_read_clk,
+	.shift	= 20,
+	.mask	= CLOCKSOURCE_MASK(32),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+void hw_timer_init(void)
+{
+	mcfslt_cycles_per_jiffy = MCF_BUSCLK / HZ;
+	/*
+	 *	The coldfire slice timer (SLT) runs from STCNT to 0 included,
+	 *	then STCNT again and so on.  It counts thus actually
+	 *	STCNT + 1 steps for 1 tick, not STCNT.  So if you want
+	 *	n cycles, initialize STCNT with n - 1.
+	 */
+	__raw_writel(mcfslt_cycles_per_jiffy - 1, TA(MCFSLT_STCNT));
+	__raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
+								TA(MCFSLT_SCR));
+	/* initialize mcfslt_cnt knowing that slice timers count down */
+	mcfslt_cnt = mcfslt_cycles_per_jiffy;
+
+	setup_irq(MCF_IRQ_TIMER, &mcfslt_timer_irq);
+
+	mcfslt_clk.mult = clocksource_hz2mult(MCF_BUSCLK, mcfslt_clk.shift);
+	clocksource_register(&mcfslt_clk);
+
+#ifdef CONFIG_HIGHPROFILE
+	mcfslt_profile_init();
+#endif
+}