source: mainline/kernel/genarch/src/drivers/am335x/timer.c@ a1b9f63

/*
 * Copyright (c) 2012 Maurizio Lombardi
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/** @addtogroup genarch
 * @{
 */
/**
 * @file
 * @brief Texas Instruments AM335x timer driver.
 */

#include <assert.h>
#include <genarch/drivers/am335x/timer.h>
#include <mm/km.h>
#include <errno.h>

typedef enum {
        REG_TCLR = 0x00,
        REG_TCRR = 0x01,
        REG_TLDR = 0x02,
        REG_TTGR = 0x04
} timer_reg_t;

typedef struct timer_regs_mmap {
        uintptr_t base;
        size_t size;
} timer_regs_mmap_t;

static const timer_regs_mmap_t regs_map[TIMERS_MAX] = {
        { .base = AM335x_DMTIMER0_BASE_ADDRESS, .size = AM335x_DMTIMER0_SIZE },
        { 0, 0 }, /* DMTIMER1 is not supported by this driver */
        { .base = AM335x_DMTIMER2_BASE_ADDRESS, .size = AM335x_DMTIMER2_SIZE },
        { .base = AM335x_DMTIMER3_BASE_ADDRESS, .size = AM335x_DMTIMER3_SIZE },
        { .base = AM335x_DMTIMER4_BASE_ADDRESS, .size = AM335x_DMTIMER4_SIZE },
        { .base = AM335x_DMTIMER5_BASE_ADDRESS, .size = AM335x_DMTIMER5_SIZE },
        { .base = AM335x_DMTIMER6_BASE_ADDRESS, .size = AM335x_DMTIMER6_SIZE },
        { .base = AM335x_DMTIMER7_BASE_ADDRESS, .size = AM335x_DMTIMER7_SIZE },
};

static void
write_register_posted(am335x_timer_t *timer, timer_reg_t reg, uint32_t value)
{
        am335x_timer_regs_t *regs = timer->regs;

        while (regs->twps & reg)
                ;

        switch (reg) {
        default:
                return;
        case REG_TCLR:
                regs->tclr = value;
                break;
        case REG_TCRR:
                regs->tcrr = value;
                break;
        case REG_TLDR:
                regs->tldr = value;
                break;
        }
}

errno_t
am335x_timer_init(am335x_timer_t *timer, am335x_timer_id_t id, unsigned hz,
    unsigned srcclk_hz)
{
        uintptr_t base_addr;
        size_t size;

        assert(id < TIMERS_MAX);
        assert(timer != NULL);

        if (id == DMTIMER1_1MS)
                return ENOTSUP; /* Not supported yet */

        base_addr = regs_map[id].base;
        size = regs_map[id].size;

        timer->regs = (void *) km_map(base_addr, size, KM_NATURAL_ALIGNMENT,
            PAGE_NOT_CACHEABLE);
        assert(timer->regs != NULL);

        timer->id = id;

        am335x_timer_regs_t *regs = timer->regs;

        /* Enable the posted mode of operation */
        regs->tsicr |= AM335x_TIMER_TSICR_POSTED_FLAG;

        /* Stop the timer */
        am335x_timer_stop(timer);

        /* Perform a soft reset */
        am335x_timer_reset(timer);

        unsigned tclr = regs->tclr;

        /* Disable compare mode */
        tclr &= ~AM335x_TIMER_TCLR_CE_FLAG;

        /* Enable auto-reload mode */
        tclr |= AM335x_TIMER_TCLR_AR_FLAG;

        write_register_posted(timer, REG_TCLR, tclr);

        /* Disable the emulation mode */
        regs->tiocp_cfg |= AM335x_TIMER_TIOCPCFG_EMUFREE_FLAG;

        unsigned const count = 0xFFFFFFFF - (srcclk_hz / hz + 1);
        write_register_posted(timer, REG_TCRR, count);
        write_register_posted(timer, REG_TLDR, count);

        return EOK;
}

void
am335x_timer_intr_ack(am335x_timer_t *timer)
{
        /* Clear pending OVF event */
        timer->regs->irqstatus |= AM335x_TIMER_IRQSTATUS_OVF_FLAG;
}

void
am335x_timer_reset(am335x_timer_t *timer)
{
        /* Initiate soft reset */
        timer->regs->tiocp_cfg |= AM335x_TIMER_TIOCPCFG_SOFTRESET_FLAG;
        /* Wait until the reset is done */
        while (timer->regs->tiocp_cfg & AM335x_TIMER_TIOCPCFG_SOFTRESET_FLAG)
                ;
}

void
am335x_timer_stop(am335x_timer_t *timer)
{
        /* Disable the interrupt */
        timer->regs->irqenable_clr |= AM335x_TIMER_IRQENABLE_CLR_OVF_FLAG;
        timer->regs->irqwakeen &= ~AM335x_TIMER_IRQWAKEEN_OVF_FLAG;
        /* Stop the timer */
        write_register_posted(timer, REG_TCLR,
            timer->regs->tclr & ~AM335x_TIMER_TCLR_ST_FLAG);
}

void
am335x_timer_start(am335x_timer_t *timer)
{
        /* Enable the interrupt */
        timer->regs->irqenable_set |= AM335x_TIMER_IRQENABLE_SET_OVF_FLAG;
        timer->regs->irqwakeen |= AM335x_TIMER_IRQWAKEEN_OVF_FLAG;
        /* Start the clock */
        write_register_posted(timer, REG_TCLR,
            timer->regs->tclr | AM335x_TIMER_TCLR_ST_FLAG);
}

/**
 * @}
 */