--- /dev/null
+/*
+ * Emma Mobile Timer Support - STI
+ *
+ * Copyright (C) 2012 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/io.h>
+#include <linux/clk.h>
+#include <linux/irq.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
+
+struct em_sti_priv {
+ void __iomem *base;
+ struct clk *clk;
+ struct platform_device *pdev;
+ unsigned int active[USER_NR];
+ unsigned long rate;
+ raw_spinlock_t lock;
+ struct clock_event_device ced;
+ struct clocksource cs;
+};
+
+#define STI_CONTROL 0x00
+#define STI_COMPA_H 0x10
+#define STI_COMPA_L 0x14
+#define STI_COMPB_H 0x18
+#define STI_COMPB_L 0x1c
+#define STI_COUNT_H 0x20
+#define STI_COUNT_L 0x24
+#define STI_COUNT_RAW_H 0x28
+#define STI_COUNT_RAW_L 0x2c
+#define STI_SET_H 0x30
+#define STI_SET_L 0x34
+#define STI_INTSTATUS 0x40
+#define STI_INTRAWSTATUS 0x44
+#define STI_INTENSET 0x48
+#define STI_INTENCLR 0x4c
+#define STI_INTFFCLR 0x50
+
+static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
+{
+ return ioread32(p->base + offs);
+}
+
+static inline void em_sti_write(struct em_sti_priv *p, int offs,
+ unsigned long value)
+{
+ iowrite32(value, p->base + offs);
+}
+
+static int em_sti_enable(struct em_sti_priv *p)
+{
+ int ret;
+
+ /* enable clock */
+ ret = clk_prepare_enable(p->clk);
+ if (ret) {
+ dev_err(&p->pdev->dev, "cannot enable clock\n");
+ return ret;
+ }
+
+ /* configure channel, periodic mode and maximum timeout */
+ p->rate = clk_get_rate(p->clk);
+
+ /* reset the counter */
+ em_sti_write(p, STI_SET_H, 0x40000000);
+ em_sti_write(p, STI_SET_L, 0x00000000);
+
+ /* mask and clear pending interrupts */
+ em_sti_write(p, STI_INTENCLR, 3);
+ em_sti_write(p, STI_INTFFCLR, 3);
+
+ /* enable updates of counter registers */
+ em_sti_write(p, STI_CONTROL, 1);
+
+ return 0;
+}
+
+static void em_sti_disable(struct em_sti_priv *p)
+{
+ /* mask interrupts */
+ em_sti_write(p, STI_INTENCLR, 3);
+
+ /* stop clock */
+ clk_disable_unprepare(p->clk);
+}
+
+static cycle_t em_sti_count(struct em_sti_priv *p)
+{
+ cycle_t ticks;
+ unsigned long flags;
+
+ /* the STI hardware buffers the 48-bit count, but to
+ * break it out into two 32-bit access the registers
+ * must be accessed in a certain order.
+ * Always read STI_COUNT_H before STI_COUNT_L.
+ */
+ raw_spin_lock_irqsave(&p->lock, flags);
+ ticks = (cycle_t)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
+ ticks |= em_sti_read(p, STI_COUNT_L);
+ raw_spin_unlock_irqrestore(&p->lock, flags);
+
+ return ticks;
+}
+
+static cycle_t em_sti_set_next(struct em_sti_priv *p, cycle_t next)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&p->lock, flags);
+
+ /* mask compare A interrupt */
+ em_sti_write(p, STI_INTENCLR, 1);
+
+ /* update compare A value */
+ em_sti_write(p, STI_COMPA_H, next >> 32);
+ em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
+
+ /* clear compare A interrupt source */
+ em_sti_write(p, STI_INTFFCLR, 1);
+
+ /* unmask compare A interrupt */
+ em_sti_write(p, STI_INTENSET, 1);
+
+ raw_spin_unlock_irqrestore(&p->lock, flags);
+
+ return next;
+}
+
+static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
+{
+ struct em_sti_priv *p = dev_id;
+
+ p->ced.event_handler(&p->ced);
+ return IRQ_HANDLED;
+}
+
+static int em_sti_start(struct em_sti_priv *p, unsigned int user)
+{
+ unsigned long flags;
+ int used_before;
+ int ret = 0;
+
+ raw_spin_lock_irqsave(&p->lock, flags);
+ used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
+ if (!used_before)
+ ret = em_sti_enable(p);
+
+ if (!ret)
+ p->active[user] = 1;
+ raw_spin_unlock_irqrestore(&p->lock, flags);
+
+ return ret;
+}
+
+static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
+{
+ unsigned long flags;
+ int used_before, used_after;
+
+ raw_spin_lock_irqsave(&p->lock, flags);
+ used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
+ p->active[user] = 0;
+ used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
+
+ if (used_before && !used_after)
+ em_sti_disable(p);
+ raw_spin_unlock_irqrestore(&p->lock, flags);
+}
+
+static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
+{
+ return container_of(cs, struct em_sti_priv, cs);
+}
+
+static cycle_t em_sti_clocksource_read(struct clocksource *cs)
+{
+ return em_sti_count(cs_to_em_sti(cs));
+}
+
+static int em_sti_clocksource_enable(struct clocksource *cs)
+{
+ int ret;
+ struct em_sti_priv *p = cs_to_em_sti(cs);
+
+ ret = em_sti_start(p, USER_CLOCKSOURCE);
+ if (!ret)
+ __clocksource_update_freq_hz(cs, p->rate);
+ return ret;
+}
+
+static void em_sti_clocksource_disable(struct clocksource *cs)
+{
+ em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
+}
+
+static void em_sti_clocksource_resume(struct clocksource *cs)
+{
+ em_sti_clocksource_enable(cs);
+}
+
+static int em_sti_register_clocksource(struct em_sti_priv *p)
+{
+ struct clocksource *cs = &p->cs;
+
+ memset(cs, 0, sizeof(*cs));
+ cs->name = dev_name(&p->pdev->dev);
+ cs->rating = 200;
+ cs->read = em_sti_clocksource_read;
+ cs->enable = em_sti_clocksource_enable;
+ cs->disable = em_sti_clocksource_disable;
+ cs->suspend = em_sti_clocksource_disable;
+ cs->resume = em_sti_clocksource_resume;
+ cs->mask = CLOCKSOURCE_MASK(48);
+ cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+ dev_info(&p->pdev->dev, "used as clock source\n");
+
+ /* Register with dummy 1 Hz value, gets updated in ->enable() */
+ clocksource_register_hz(cs, 1);
+ return 0;
+}
+
+static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
+{
+ return container_of(ced, struct em_sti_priv, ced);
+}
+
+static void em_sti_clock_event_mode(enum clock_event_mode mode,
+ struct clock_event_device *ced)
+{
+ struct em_sti_priv *p = ced_to_em_sti(ced);
+
+ /* deal with old setting first */
+ switch (ced->mode) {
+ case CLOCK_EVT_MODE_ONESHOT:
+ em_sti_stop(p, USER_CLOCKEVENT);
+ break;
+ default:
+ break;
+ }
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_ONESHOT:
+ dev_info(&p->pdev->dev, "used for oneshot clock events\n");
+ em_sti_start(p, USER_CLOCKEVENT);
+ clockevents_config(&p->ced, p->rate);
+ break;
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ case CLOCK_EVT_MODE_UNUSED:
+ em_sti_stop(p, USER_CLOCKEVENT);
+ break;
+ default:
+ break;
+ }
+}
+
+static int em_sti_clock_event_next(unsigned long delta,
+ struct clock_event_device *ced)
+{
+ struct em_sti_priv *p = ced_to_em_sti(ced);
+ cycle_t next;
+ int safe;
+
+ next = em_sti_set_next(p, em_sti_count(p) + delta);
+ safe = em_sti_count(p) < (next - 1);
+
+ return !safe;
+}
+
+static void em_sti_register_clockevent(struct em_sti_priv *p)
+{
+ struct clock_event_device *ced = &p->ced;
+
+ memset(ced, 0, sizeof(*ced));
+ ced->name = dev_name(&p->pdev->dev);
+ ced->features = CLOCK_EVT_FEAT_ONESHOT;
+ ced->rating = 200;
+ ced->cpumask = cpu_possible_mask;
+ ced->set_next_event = em_sti_clock_event_next;
+ ced->set_mode = em_sti_clock_event_mode;
+
+ dev_info(&p->pdev->dev, "used for clock events\n");
+
+ /* Register with dummy 1 Hz value, gets updated in ->set_mode() */
+ clockevents_config_and_register(ced, 1, 2, 0xffffffff);
+}
+
+static int em_sti_probe(struct platform_device *pdev)
+{
+ struct em_sti_priv *p;
+ struct resource *res;
+ int irq;
+
+ p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
+ if (p == NULL)
+ return -ENOMEM;
+
+ p->pdev = pdev;
+ platform_set_drvdata(pdev, p);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_err(&pdev->dev, "failed to get irq\n");
+ return -EINVAL;
+ }
+
+ /* map memory, let base point to the STI instance */
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ p->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(p->base))
+ return PTR_ERR(p->base);
+
+ /* get hold of clock */
+ p->clk = devm_clk_get(&pdev->dev, "sclk");
+ if (IS_ERR(p->clk)) {
+ dev_err(&pdev->dev, "cannot get clock\n");
+ return PTR_ERR(p->clk);
+ }
+
+ if (devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
+ IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
+ dev_name(&pdev->dev), p)) {
+ dev_err(&pdev->dev, "failed to request low IRQ\n");
+ return -ENOENT;
+ }
+
+ raw_spin_lock_init(&p->lock);
+ em_sti_register_clockevent(p);
+ em_sti_register_clocksource(p);
+ return 0;
+}
+
+static int em_sti_remove(struct platform_device *pdev)
+{
+ return -EBUSY; /* cannot unregister clockevent and clocksource */
+}
+
+static const struct of_device_id em_sti_dt_ids[] = {
+ { .compatible = "renesas,em-sti", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
+
+static struct platform_driver em_sti_device_driver = {
+ .probe = em_sti_probe,
+ .remove = em_sti_remove,
+ .driver = {
+ .name = "em_sti",
+ .of_match_table = em_sti_dt_ids,
+ }
+};
+
+static int __init em_sti_init(void)
+{
+ return platform_driver_register(&em_sti_device_driver);
+}
+
+static void __exit em_sti_exit(void)
+{
+ platform_driver_unregister(&em_sti_device_driver);
+}
+
+subsys_initcall(em_sti_init);
+module_exit(em_sti_exit);
+
+MODULE_AUTHOR("Magnus Damm");
+MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
+MODULE_LICENSE("GPL v2");
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