[PATCH] clocksource: SuperH MTU2 Timer driver

Magnus Damm
2009-04-30T07:02:49Z

From: Magnus Damm <damm@igel.co.jp>

This patch adds a MTU2 driver for the SuperH architecture.

The MTU2 driver is a platform driver with early platform
support to allow using a MTU2 channel as only clockevent
during system bootup.

Clocksource on sh2a is currently unsupported due to code
generation issues with 64-bit math, so at this point only
periodic clockevent support is in place.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
---

Tested on a rsk7203 board with a sh7203 processor.

arch/sh/Kconfig | 11 +
drivers/clocksource/Makefile | 1
drivers/clocksource/sh_mtu2.c | 357 +++++++++++++++++++++++++++++++++++++++++
include/linux/sh_mtu2.h | 12 +
4 files changed, 381 insertions(+)

--- 0007/arch/sh/Kconfig
+++ work/arch/sh/Kconfig 2009-04-29 23:11:09.000000000 +0900
@@ -113,6 +113,9 @@ config SYS_SUPPORTS_PCI
config SYS_SUPPORTS_CMT
bool

+config SYS_SUPPORTS_MTU2
+ bool
+
config STACKTRACE_SUPPORT
def_bool y

@@ -478,6 +481,14 @@ config SH_MTU2
help
This enables the use of the MTU2 as the system timer.

+config SH_TIMER_MTU2
+ bool "MTU2 timer driver"
+ depends on SYS_SUPPORTS_MTU2 && !SH_MTU2
+ default y
+ select GENERIC_CLOCKEVENTS
+ help
+ This enables build of the MTU2 timer driver.
+
config SH_TIMER_IRQ
int
default "28" if CPU_SUBTYPE_SH7780 || CPU_SUBTYPE_SH7785 || \
--- 0001/drivers/clocksource/Makefile
+++ work/drivers/clocksource/Makefile 2009-04-29 23:11:09.000000000 +0900
@@ -3,3 +3,4 @@ obj-$(CONFIG_X86_CYCLONE_TIMER) += cyclo
obj-$(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
--- /dev/null
+++ work/drivers/clocksource/sh_mtu2.c 2009-04-29 23:11:48.000000000 +0900
@@ -0,0 +1,357 @@
+/*
+ * SuperH Timer Support - MTU2
+ *
+ * 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/clockchips.h>
+#include <linux/sh_mtu2.h>
+
+struct sh_mtu2_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;
+};
+
+static DEFINE_SPINLOCK(sh_mtu2_lock);
+
+#define TSTR -1 /* shared register */
+#define TCR 0 /* channel register */
+#define TMDR 1 /* channel register */
+#define TIOR 2 /* channel register */
+#define TIER 3 /* channel register */
+#define TSR 4 /* channel register */
+#define TCNT 5 /* channel register */
+#define TGR 6 /* channel register */
+
+static unsigned long mtu2_reg_offs[] = {
+ [TCR] = 0,
+ [TMDR] = 1,
+ [TIOR] = 2,
+ [TIER] = 4,
+ [TSR] = 5,
+ [TCNT] = 6,
+ [TGR] = 8,
+};
+
+static inline unsigned long sh_mtu2_read(struct sh_mtu2_priv *p, int reg_nr)
+{
+ struct sh_mtu2_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 = mtu2_reg_offs[reg_nr];
+
+ if ((reg_nr = TCNT) || (reg_nr = TGR))
+ return ioread16(base + offs);
+ else
+ return ioread8(base + offs);
+}
+
+static inline void sh_mtu2_write(struct sh_mtu2_priv *p, int reg_nr,
+ unsigned long value)
+{
+ struct sh_mtu2_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 = mtu2_reg_offs[reg_nr];
+
+ if ((reg_nr = TCNT) || (reg_nr = TGR))
+ iowrite16(value, base + offs);
+ else
+ iowrite8(value, base + offs);
+}
+
+static void sh_mtu2_start_stop_ch(struct sh_mtu2_priv *p, int start)
+{
+ struct sh_mtu2_config *cfg = p->pdev->dev.platform_data;
+ unsigned long flags, value;
+
+ /* start stop register shared by multiple timer channels */
+ spin_lock_irqsave(&sh_mtu2_lock, flags);
+ value = sh_mtu2_read(p, TSTR);
+
+ if (start)
+ value |= 1 << cfg->timer_bit;
+ else
+ value &= ~(1 << cfg->timer_bit);
+
+ sh_mtu2_write(p, TSTR, value);
+ spin_unlock_irqrestore(&sh_mtu2_lock, flags);
+}
+
+static int sh_mtu2_enable(struct sh_mtu2_priv *p)
+{
+ struct sh_mtu2_config *cfg = p->pdev->dev.platform_data;
+ int ret;
+
+ /* enable clock */
+ ret = clk_enable(p->clk);
+ if (ret) {
+ pr_err("sh_mtu2: cannot enable clock \"%s\"\n", cfg->clk);
+ return ret;
+ }
+
+ /* make sure channel is disabled */
+ sh_mtu2_start_stop_ch(p, 0);
+
+ p->rate = clk_get_rate(p->clk) / 64;
+ p->periodic = (p->rate + HZ/2) / HZ;
+
+ /* "Periodic Counter Operation" */
+ sh_mtu2_write(p, TCR, 0x23); /* TGRA clear, divide clock by 64 */
+ sh_mtu2_write(p, TIOR, 0);
+ sh_mtu2_write(p, TGR, p->periodic);
+ sh_mtu2_write(p, TCNT, 0);
+ sh_mtu2_write(p, TMDR, 0);
+ sh_mtu2_write(p, TIER, 0x01);
+
+ /* enable channel */
+ sh_mtu2_start_stop_ch(p, 1);
+
+ return 0;
+}
+
+static void sh_mtu2_disable(struct sh_mtu2_priv *p)
+{
+ /* disable channel */
+ sh_mtu2_start_stop_ch(p, 0);
+
+ /* stop clock */
+ clk_disable(p->clk);
+}
+
+static irqreturn_t sh_mtu2_interrupt(int irq, void *dev_id)
+{
+ struct sh_mtu2_priv *p = dev_id;
+
+ /* acknowledge interrupt */
+ sh_mtu2_read(p, TSR);
+ sh_mtu2_write(p, TSR, 0xfe);
+
+ /* notify clockevent layer */
+ p->ced.event_handler(&p->ced);
+ return IRQ_HANDLED;
+}
+
+static struct sh_mtu2_priv *ced_to_sh_mtu2(struct clock_event_device *ced)
+{
+ return container_of(ced, struct sh_mtu2_priv, ced);
+}
+
+static void sh_mtu2_clock_event_mode(enum clock_event_mode mode,
+ struct clock_event_device *ced)
+{
+ struct sh_mtu2_priv *p = ced_to_sh_mtu2(ced);
+ int disabled = 0;
+
+ /* deal with old setting first */
+ switch (ced->mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ sh_mtu2_disable(p);
+ disabled = 1;
+ break;
+ default:
+ break;
+ }
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ pr_info("sh_mtu2: %s used for periodic clock events\n",
+ ced->name);
+ sh_mtu2_enable(p);
+ break;
+ case CLOCK_EVT_MODE_UNUSED:
+ if (!disabled)
+ sh_mtu2_disable(p);
+ break;
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ default:
+ break;
+ }
+}
+
+static void sh_mtu2_register_clockevent(struct sh_mtu2_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->rating = rating;
+ ced->cpumask = cpumask_of(0);
+ ced->set_mode = sh_mtu2_clock_event_mode;
+
+ ret = setup_irq(p->irqaction.irq, &p->irqaction);
+ if (ret) {
+ pr_err("sh_mtu2: failed to request irq %d\n",
+ p->irqaction.irq);
+ return;
+ }
+
+ pr_info("sh_mtu2: %s used for clock events\n", ced->name);
+ clockevents_register_device(ced);
+}
+
+int sh_mtu2_register(struct sh_mtu2_priv *p, char *name,
+ unsigned long clockevent_rating)
+{
+ if (clockevent_rating)
+ sh_mtu2_register_clockevent(p, name, clockevent_rating);
+
+ return 0;
+}
+
+static int sh_mtu2_setup(struct sh_mtu2_priv *p, struct platform_device *pdev)
+{
+ struct sh_mtu2_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_mtu2: 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_mtu2_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_mtu2: cannot get clock \"%s\"\n", cfg->clk);
+ ret = PTR_ERR(p->clk);
+ goto err1;
+ }
+
+ return sh_mtu2_register(p, cfg->name, cfg->clockevent_rating);
+ err1:
+ iounmap(p->mapbase);
+ err0:
+ return ret;
+}
+
+static int __devinit sh_mtu2_probe(struct platform_device *pdev)
+{
+ struct sh_mtu2_priv *p = platform_get_drvdata(pdev);
+ struct sh_mtu2_config *cfg = pdev->dev.platform_data;
+ int ret;
+
+ if (p) {
+ pr_info("sh_mtu2: %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_mtu2_setup(p, pdev);
+ if (ret) {
+ kfree(p);
+ platform_set_drvdata(pdev, NULL);
+ }
+ return ret;
+}
+
+static int __devexit sh_mtu2_remove(struct platform_device *pdev)
+{
+ return -EBUSY; /* cannot unregister clockevent */
+}
+
+static struct platform_driver sh_mtu2_device_driver = {
+ .probe = sh_mtu2_probe,
+ .remove = __devexit_p(sh_mtu2_remove),
+ .driver = {
+ .name = "sh_mtu2",
+ }
+};
+
+static int __init sh_mtu2_init(void)
+{
+ return platform_driver_register(&sh_mtu2_device_driver);
+}
+
+static void __exit sh_mtu2_exit(void)
+{
+ platform_driver_unregister(&sh_mtu2_device_driver);
+}
+
+early_platform_init("earlytimer", &sh_mtu2_device_driver);
+module_init(sh_mtu2_init);
+module_exit(sh_mtu2_exit);
+
+MODULE_AUTHOR("Magnus Damm");
+MODULE_DESCRIPTION("SuperH MTU2 Timer Driver");
+MODULE_LICENSE("GPL v2");
--- /dev/null
+++ work/include/linux/sh_mtu2.h 2009-04-29 23:11:09.000000000 +0900
@@ -0,0 +1,12 @@
+#ifndef __SH_MTU2_H__
+#define __SH_MTU2_H__
+
+struct sh_mtu2_config {
+ char *name;
+ int channel_offset;
+ int timer_bit;
+ char *clk;
+ unsigned long clockevent_rating;
+};
+
+#endif /* __SH_MTU2_H__ */