ARM: 6597/1: Add basic architecture support for VIA/WonderMedia 85xx SoC's

This adds support for the family of Systems-on-Chip produced initially
by VIA and now its subsidiary WonderMedia that have recently become
widespread in lower-end Chinese ARM-based tablets and netbooks.

Support is included for both VT8500 and WM8505, selectable by a
configuration switch at kernel build time.

Included are basic machine initialization files, register and
interrupt definitions, support for the on-chip interrupt controller,
high-precision OS timer, GPIO lines, necessary macros for early debug,
pulse-width-modulated outputs control, as well as platform device
configurations for the specific drivers implemented elsewhere.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 155 insertions, 0 deletions

diff --git a/arch/arm/mach-vt8500/timer.c b/arch/arm/mach-vt8500/timer.c
new file mode 100644
index 000000000000..d5376c592ab6
--- /dev/null
+++ b/arch/arm/mach-vt8500/timer.c
@@ -0,0 +1,155 @@
+/*
+ *  arch/arm/mach-vt8500/timer.c
+ *
+ *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/delay.h>
+
+#include <asm/mach/time.h>
+
+#include "devices.h"
+
+#define VT8500_TIMER_OFFSET     0x0100
+#define TIMER_MATCH_VAL         0x0000
+#define TIMER_COUNT_VAL         0x0010
+#define TIMER_STATUS_VAL        0x0014
+#define TIMER_IER_VAL           0x001c          /* interrupt enable */
+#define TIMER_CTRL_VAL          0x0020
+#define TIMER_AS_VAL            0x0024          /* access status */
+#define TIMER_COUNT_R_ACTIVE    (1 << 5)        /* not ready for read */
+#define TIMER_COUNT_W_ACTIVE    (1 << 4)        /* not ready for write */
+#define TIMER_MATCH_W_ACTIVE    (1 << 0)        /* not ready for write */
+#define VT8500_TIMER_HZ         3000000
+
+#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
+
+static void __iomem *regbase;
+
+static cycle_t vt8500_timer_read(struct clocksource *cs)
+{
+        int loops = msecs_to_loops(10);
+        writel(3, regbase + TIMER_CTRL_VAL);
+        while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)
+                                                && --loops)
+                cpu_relax();
+        return readl(regbase + TIMER_COUNT_VAL);
+}
+
+struct clocksource clocksource = {
+        .name           = "vt8500_timer",
+        .rating         = 200,
+        .read           = vt8500_timer_read,
+        .mask           = CLOCKSOURCE_MASK(32),
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int vt8500_timer_set_next_event(unsigned long cycles,
+                                    struct clock_event_device *evt)
+{
+        int loops = msecs_to_loops(10);
+        cycle_t alarm = clocksource.read(&clocksource) + cycles;
+        while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)
+                                                && --loops)
+                cpu_relax();
+        writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);
+
+        if ((signed)(alarm - clocksource.read(&clocksource)) <= 16)
+                return -ETIME;
+
+        writel(1, regbase + TIMER_IER_VAL);
+
+        return 0;
+}
+
+static void vt8500_timer_set_mode(enum clock_event_mode mode,
+                              struct clock_event_device *evt)
+{
+        switch (mode) {
+        case CLOCK_EVT_MODE_RESUME:
+        case CLOCK_EVT_MODE_PERIODIC:
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+                writel(readl(regbase + TIMER_CTRL_VAL) | 1,
+                        regbase + TIMER_CTRL_VAL);
+                writel(0, regbase + TIMER_IER_VAL);
+                break;
+        }
+}
+
+struct clock_event_device clockevent = {
+        .name           = "vt8500_timer",
+        .features       = CLOCK_EVT_FEAT_ONESHOT,
+        .rating         = 200,
+        .set_next_event = vt8500_timer_set_next_event,
+        .set_mode       = vt8500_timer_set_mode,
+};
+
+static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = dev_id;
+        writel(0xf, regbase + TIMER_STATUS_VAL);
+        evt->event_handler(evt);
+
+        return IRQ_HANDLED;
+}
+
+struct irqaction irq = {
+        .name    = "vt8500_timer",
+        .flags   = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+        .handler = vt8500_timer_interrupt,
+        .dev_id  = &clockevent,
+};
+
+static void __init vt8500_timer_init(void)
+{
+        regbase = ioremap(wmt_pmc_base + VT8500_TIMER_OFFSET, 0x28);
+        if (!regbase)
+                printk(KERN_ERR "vt8500_timer_init: failed to map MMIO registers\n");
+
+        writel(1, regbase + TIMER_CTRL_VAL);
+        writel(0xf, regbase + TIMER_STATUS_VAL);
+        writel(~0, regbase + TIMER_MATCH_VAL);
+
+        if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ))
+                printk(KERN_ERR "vt8500_timer_init: clocksource_register failed for %s\n",
+                                        clocksource.name);
+
+        clockevents_calc_mult_shift(&clockevent, VT8500_TIMER_HZ, 4);
+
+        /* copy-pasted from mach-msm; no idea */
+        clockevent.max_delta_ns =
+                clockevent_delta2ns(0xf0000000, &clockevent);
+        clockevent.min_delta_ns = clockevent_delta2ns(4, &clockevent);
+        clockevent.cpumask = cpumask_of(0);
+
+        if (setup_irq(wmt_timer_irq, &irq))
+                printk(KERN_ERR "vt8500_timer_init: setup_irq failed for %s\n",
+                                        clockevent.name);
+        clockevents_register_device(&clockevent);
+}
+
+struct sys_timer vt8500_timer = {
+        .init = vt8500_timer_init
+};