clocksource: SuperH TMU Timer driver

This patch adds a TMU driver for the SuperH architecture.

The TMU driver is a platform driver with early platform
support to allow using a TMU channel as clockevent or
clocksource during system bootup or later.

Clocksource or clockevent can be selected.
Both periodic and oneshot clockevents are supported.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

4 files changed, 487 insertions, 0 deletions

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index bda3dc1b0c26..1f74737c4f20 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -116,6 +116,9 @@ config SYS_SUPPORTS_CMT
 config SYS_SUPPORTS_MTU2
         bool
 
+config SYS_SUPPORTS_TMU
+        bool
+
 config STACKTRACE_SUPPORT
         def_bool y
 
@@ -470,6 +473,15 @@ config SH_TMU
         help
           This enables the use of the TMU as the system timer.
 
+config SH_TIMER_TMU
+        bool "TMU timer driver"
+        depends on !SH_TMU && SYS_SUPPORTS_TMU
+        default y
+        select GENERIC_TIME
+        select GENERIC_CLOCKEVENTS
+        help
+          This enables the build of the TMU timer driver.
+
 config SH_TIMER_CMT
         bool "CMT timer driver"
         depends on SYS_SUPPORTS_CMT
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 9785586dc8c4..eef216f7f61d 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -4,3 +4,4 @@ obj-$(CONFIG_X86_PM_TIMER)	+= acpi_pm.o
 obj-$(CONFIG_SCx200HR_TIMER)    += scx200_hrt.o
 obj-$(CONFIG_SH_TIMER_CMT)      += sh_cmt.o
 obj-$(CONFIG_SH_TIMER_MTU2)     += sh_mtu2.o
+obj-$(CONFIG_SH_TIMER_TMU)      += sh_tmu.o
diff --git a/drivers/clocksource/sh_tmu.c b/drivers/clocksource/sh_tmu.c
new file mode 100644
index 000000000000..21bd77aa6a34
--- /dev/null
+++ b/drivers/clocksource/sh_tmu.c
@@ -0,0 +1,461 @@
+/*
+ * SuperH Timer Support - TMU
+ *
+ *  Copyright (C) 2009 Magnus Damm
+ *
+ * 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
+ *
+ * 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/init.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/irq.h>
+#include <linux/err.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/sh_tmu.h>
+
+struct sh_tmu_priv {
+        void __iomem *mapbase;
+        struct clk *clk;
+        struct irqaction irqaction;
+        struct platform_device *pdev;
+        unsigned long rate;
+        unsigned long periodic;
+        struct clock_event_device ced;
+        struct clocksource cs;
+};
+
+static DEFINE_SPINLOCK(sh_tmu_lock);
+
+#define TSTR -1 /* shared register */
+#define TCOR  0 /* channel register */
+#define TCNT 1 /* channel register */
+#define TCR 2 /* channel register */
+
+static inline unsigned long sh_tmu_read(struct sh_tmu_priv *p, int reg_nr)
+{
+        struct sh_tmu_config *cfg = p->pdev->dev.platform_data;
+        void __iomem *base = p->mapbase;
+        unsigned long offs;
+
+        if (reg_nr == TSTR)
+                return ioread8(base - cfg->channel_offset);
+
+        offs = reg_nr << 2;
+
+        if (reg_nr == TCR)
+                return ioread16(base + offs);
+        else
+                return ioread32(base + offs);
+}
+
+static inline void sh_tmu_write(struct sh_tmu_priv *p, int reg_nr,
+                                unsigned long value)
+{
+        struct sh_tmu_config *cfg = p->pdev->dev.platform_data;
+        void __iomem *base = p->mapbase;
+        unsigned long offs;
+
+        if (reg_nr == TSTR) {
+                iowrite8(value, base - cfg->channel_offset);
+                return;
+        }
+
+        offs = reg_nr << 2;
+
+        if (reg_nr == TCR)
+                iowrite16(value, base + offs);
+        else
+                iowrite32(value, base + offs);
+}
+
+static void sh_tmu_start_stop_ch(struct sh_tmu_priv *p, int start)
+{
+        struct sh_tmu_config *cfg = p->pdev->dev.platform_data;
+        unsigned long flags, value;
+
+        /* start stop register shared by multiple timer channels */
+        spin_lock_irqsave(&sh_tmu_lock, flags);
+        value = sh_tmu_read(p, TSTR);
+
+        if (start)
+                value |= 1 << cfg->timer_bit;
+        else
+                value &= ~(1 << cfg->timer_bit);
+
+        sh_tmu_write(p, TSTR, value);
+        spin_unlock_irqrestore(&sh_tmu_lock, flags);
+}
+
+static int sh_tmu_enable(struct sh_tmu_priv *p)
+{
+        struct sh_tmu_config *cfg = p->pdev->dev.platform_data;
+        int ret;
+
+        /* enable clock */
+        ret = clk_enable(p->clk);
+        if (ret) {
+                pr_err("sh_tmu: cannot enable clock \"%s\"\n", cfg->clk);
+                return ret;
+        }
+
+        /* make sure channel is disabled */
+        sh_tmu_start_stop_ch(p, 0);
+
+        /* maximum timeout */
+        sh_tmu_write(p, TCOR, 0xffffffff);
+        sh_tmu_write(p, TCNT, 0xffffffff);
+
+        /* configure channel to parent clock / 4, irq off */
+        p->rate = clk_get_rate(p->clk) / 4;
+        sh_tmu_write(p, TCR, 0x0000);
+
+        /* enable channel */
+        sh_tmu_start_stop_ch(p, 1);
+
+        return 0;
+}
+
+static void sh_tmu_disable(struct sh_tmu_priv *p)
+{
+        /* disable channel */
+        sh_tmu_start_stop_ch(p, 0);
+
+        /* stop clock */
+        clk_disable(p->clk);
+}
+
+static void sh_tmu_set_next(struct sh_tmu_priv *p, unsigned long delta,
+                            int periodic)
+{
+        /* stop timer */
+        sh_tmu_start_stop_ch(p, 0);
+
+        /* acknowledge interrupt */
+        sh_tmu_read(p, TCR);
+
+        /* enable interrupt */
+        sh_tmu_write(p, TCR, 0x0020);
+
+        /* reload delta value in case of periodic timer */
+        if (periodic)
+                sh_tmu_write(p, TCOR, delta);
+        else
+                sh_tmu_write(p, TCOR, 0);
+
+        sh_tmu_write(p, TCNT, delta);
+
+        /* start timer */
+        sh_tmu_start_stop_ch(p, 1);
+}
+
+static irqreturn_t sh_tmu_interrupt(int irq, void *dev_id)
+{
+        struct sh_tmu_priv *p = dev_id;
+
+        /* disable or acknowledge interrupt */
+        if (p->ced.mode == CLOCK_EVT_MODE_ONESHOT)
+                sh_tmu_write(p, TCR, 0x0000);
+        else
+                sh_tmu_write(p, TCR, 0x0020);
+
+        /* notify clockevent layer */
+        p->ced.event_handler(&p->ced);
+        return IRQ_HANDLED;
+}
+
+static struct sh_tmu_priv *cs_to_sh_tmu(struct clocksource *cs)
+{
+        return container_of(cs, struct sh_tmu_priv, cs);
+}
+
+static cycle_t sh_tmu_clocksource_read(struct clocksource *cs)
+{
+        struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
+
+        return sh_tmu_read(p, TCNT) ^ 0xffffffff;
+}
+
+static int sh_tmu_clocksource_enable(struct clocksource *cs)
+{
+        struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
+        int ret;
+
+        ret = sh_tmu_enable(p);
+        if (ret)
+                return ret;
+
+        /* TODO: calculate good shift from rate and counter bit width */
+        cs->shift = 10;
+        cs->mult = clocksource_hz2mult(p->rate, cs->shift);
+        return 0;
+}
+
+static void sh_tmu_clocksource_disable(struct clocksource *cs)
+{
+        sh_tmu_disable(cs_to_sh_tmu(cs));
+}
+
+static int sh_tmu_register_clocksource(struct sh_tmu_priv *p,
+                                       char *name, unsigned long rating)
+{
+        struct clocksource *cs = &p->cs;
+
+        cs->name = name;
+        cs->rating = rating;
+        cs->read = sh_tmu_clocksource_read;
+        cs->enable = sh_tmu_clocksource_enable;
+        cs->disable = sh_tmu_clocksource_disable;
+        cs->mask = CLOCKSOURCE_MASK(32);
+        cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
+        pr_info("sh_tmu: %s used as clock source\n", cs->name);
+        clocksource_register(cs);
+        return 0;
+}
+
+static struct sh_tmu_priv *ced_to_sh_tmu(struct clock_event_device *ced)
+{
+        return container_of(ced, struct sh_tmu_priv, ced);
+}
+
+static void sh_tmu_clock_event_start(struct sh_tmu_priv *p, int periodic)
+{
+        struct clock_event_device *ced = &p->ced;
+
+        sh_tmu_enable(p);
+
+        /* TODO: calculate good shift from rate and counter bit width */
+
+        ced->shift = 32;
+        ced->mult = div_sc(p->rate, NSEC_PER_SEC, ced->shift);
+        ced->max_delta_ns = clockevent_delta2ns(0xffffffff, ced);
+        ced->min_delta_ns = 5000;
+
+        if (periodic) {
+                p->periodic = (p->rate + HZ/2) / HZ;
+                sh_tmu_set_next(p, p->periodic, 1);
+        }
+}
+
+static void sh_tmu_clock_event_mode(enum clock_event_mode mode,
+                                    struct clock_event_device *ced)
+{
+        struct sh_tmu_priv *p = ced_to_sh_tmu(ced);
+        int disabled = 0;
+
+        /* deal with old setting first */
+        switch (ced->mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+        case CLOCK_EVT_MODE_ONESHOT:
+                sh_tmu_disable(p);
+                disabled = 1;
+                break;
+        default:
+                break;
+        }
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                pr_info("sh_tmu: %s used for periodic clock events\n",
+                        ced->name);
+                sh_tmu_clock_event_start(p, 1);
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+                pr_info("sh_tmu: %s used for oneshot clock events\n",
+                        ced->name);
+                sh_tmu_clock_event_start(p, 0);
+                break;
+        case CLOCK_EVT_MODE_UNUSED:
+                if (!disabled)
+                        sh_tmu_disable(p);
+                break;
+        case CLOCK_EVT_MODE_SHUTDOWN:
+        default:
+                break;
+        }
+}
+
+static int sh_tmu_clock_event_next(unsigned long delta,
+                                   struct clock_event_device *ced)
+{
+        struct sh_tmu_priv *p = ced_to_sh_tmu(ced);
+
+        BUG_ON(ced->mode != CLOCK_EVT_MODE_ONESHOT);
+
+        /* program new delta value */
+        sh_tmu_set_next(p, delta, 0);
+        return 0;
+}
+
+static void sh_tmu_register_clockevent(struct sh_tmu_priv *p,
+                                       char *name, unsigned long rating)
+{
+        struct clock_event_device *ced = &p->ced;
+        int ret;
+
+        memset(ced, 0, sizeof(*ced));
+
+        ced->name = name;
+        ced->features = CLOCK_EVT_FEAT_PERIODIC;
+        ced->features |= CLOCK_EVT_FEAT_ONESHOT;
+        ced->rating = rating;
+        ced->cpumask = cpumask_of(0);
+        ced->set_next_event = sh_tmu_clock_event_next;
+        ced->set_mode = sh_tmu_clock_event_mode;
+
+        ret = setup_irq(p->irqaction.irq, &p->irqaction);
+        if (ret) {
+                pr_err("sh_tmu: failed to request irq %d\n",
+                       p->irqaction.irq);
+                return;
+        }
+
+        pr_info("sh_tmu: %s used for clock events\n", ced->name);
+        clockevents_register_device(ced);
+}
+
+static int sh_tmu_register(struct sh_tmu_priv *p, char *name,
+                    unsigned long clockevent_rating,
+                    unsigned long clocksource_rating)
+{
+        if (clockevent_rating)
+                sh_tmu_register_clockevent(p, name, clockevent_rating);
+        else if (clocksource_rating)
+                sh_tmu_register_clocksource(p, name, clocksource_rating);
+
+        return 0;
+}
+
+static int sh_tmu_setup(struct sh_tmu_priv *p, struct platform_device *pdev)
+{
+        struct sh_tmu_config *cfg = pdev->dev.platform_data;
+        struct resource *res;
+        int irq, ret;
+        ret = -ENXIO;
+
+        memset(p, 0, sizeof(*p));
+        p->pdev = pdev;
+
+        if (!cfg) {
+                dev_err(&p->pdev->dev, "missing platform data\n");
+                goto err0;
+        }
+
+        platform_set_drvdata(pdev, p);
+
+        res = platform_get_resource(p->pdev, IORESOURCE_MEM, 0);
+        if (!res) {
+                dev_err(&p->pdev->dev, "failed to get I/O memory\n");
+                goto err0;
+        }
+
+        irq = platform_get_irq(p->pdev, 0);
+        if (irq < 0) {
+                dev_err(&p->pdev->dev, "failed to get irq\n");
+                goto err0;
+        }
+
+        /* map memory, let mapbase point to our channel */
+        p->mapbase = ioremap_nocache(res->start, resource_size(res));
+        if (p->mapbase == NULL) {
+                pr_err("sh_tmu: failed to remap I/O memory\n");
+                goto err0;
+        }
+
+        /* setup data for setup_irq() (too early for request_irq()) */
+        p->irqaction.name = cfg->name;
+        p->irqaction.handler = sh_tmu_interrupt;
+        p->irqaction.dev_id = p;
+        p->irqaction.irq = irq;
+        p->irqaction.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL;
+        p->irqaction.mask = CPU_MASK_NONE;
+
+        /* get hold of clock */
+        p->clk = clk_get(&p->pdev->dev, cfg->clk);
+        if (IS_ERR(p->clk)) {
+                pr_err("sh_tmu: cannot get clock \"%s\"\n", cfg->clk);
+                ret = PTR_ERR(p->clk);
+                goto err1;
+        }
+
+        return sh_tmu_register(p, cfg->name,
+                               cfg->clockevent_rating,
+                               cfg->clocksource_rating);
+ err1:
+        iounmap(p->mapbase);
+ err0:
+        return ret;
+}
+
+static int __devinit sh_tmu_probe(struct platform_device *pdev)
+{
+        struct sh_tmu_priv *p = platform_get_drvdata(pdev);
+        struct sh_tmu_config *cfg = pdev->dev.platform_data;
+        int ret;
+
+        if (p) {
+                pr_info("sh_tmu: %s kept as earlytimer\n", cfg->name);
+                return 0;
+        }
+
+        p = kmalloc(sizeof(*p), GFP_KERNEL);
+        if (p == NULL) {
+                dev_err(&pdev->dev, "failed to allocate driver data\n");
+                return -ENOMEM;
+        }
+
+        ret = sh_tmu_setup(p, pdev);
+        if (ret) {
+                kfree(p);
+                platform_set_drvdata(pdev, NULL);
+        }
+        return ret;
+}
+
+static int __devexit sh_tmu_remove(struct platform_device *pdev)
+{
+        return -EBUSY; /* cannot unregister clockevent and clocksource */
+}
+
+static struct platform_driver sh_tmu_device_driver = {
+        .probe          = sh_tmu_probe,
+        .remove         = __devexit_p(sh_tmu_remove),
+        .driver         = {
+                .name   = "sh_tmu",
+        }
+};
+
+static int __init sh_tmu_init(void)
+{
+        return platform_driver_register(&sh_tmu_device_driver);
+}
+
+static void __exit sh_tmu_exit(void)
+{
+        platform_driver_unregister(&sh_tmu_device_driver);
+}
+
+early_platform_init("earlytimer", &sh_tmu_device_driver);
+module_init(sh_tmu_init);
+module_exit(sh_tmu_exit);
+
+MODULE_AUTHOR("Magnus Damm");
+MODULE_DESCRIPTION("SuperH TMU Timer Driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/sh_tmu.h b/include/linux/sh_tmu.h
new file mode 100644
index 000000000000..b1195e8a37d0
--- /dev/null
+++ b/include/linux/sh_tmu.h
@@ -0,0 +1,13 @@
+#ifndef __SH_TMU_H__
+#define __SH_TMU_H__
+
+struct sh_tmu_config {
+        char *name;
+        unsigned long channel_offset;
+        int timer_bit;
+        char *clk;
+        unsigned long clockevent_rating;
+        unsigned long clocksource_rating;
+};
+
+#endif /* __SH_TMU_H__ */