1. 根目录:
2. drivers
3. misc
4. atmel_tclib.c

#include <linux/atmel_tc.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/of.h>

/*
 * This is a thin library to solve the problem of how to portably allocate
 * one of the TC blocks.  For simplicity, it doesn't currently expect to
 * share individual timers between different drivers.
 */

#if defined(CONFIG_AVR32)
/* AVR32 has these divide PBB */
const u8 atmel_tc_divisors[5] = { 0, 4, 8, 16, 32, };
EXPORT_SYMBOL(atmel_tc_divisors);

#elif defined(CONFIG_ARCH_AT91)
/* AT91 has these divide MCK */
const u8 atmel_tc_divisors[5] = { 2, 8, 32, 128, 0, };
EXPORT_SYMBOL(atmel_tc_divisors);

#endif

static DEFINE_SPINLOCK(tc_list_lock);
static LIST_HEAD(tc_list);

/**
 * atmel_tc_alloc - allocate a specified TC block
 * @block: which block to allocate
 *
 * Caller allocates a block.  If it is available, a pointer to a
 * pre-initialized struct atmel_tc is returned. The caller can access
 * the registers directly through the "regs" field.
 */
struct atmel_tc *atmel_tc_alloc(unsigned block)
{
	struct atmel_tc		*tc;
	struct platform_device	*pdev = NULL;

	spin_lock(&tc_list_lock);
	list_for_each_entry(tc, &tc_list, node) {
		if (tc->allocated)
			continue;

		if ((tc->pdev->dev.of_node && tc->id == block) ||
		    (tc->pdev->id == block)) {
			pdev = tc->pdev;
			tc->allocated = true;
			break;
		}
	}
	spin_unlock(&tc_list_lock);

	return pdev ? tc : NULL;
}
EXPORT_SYMBOL_GPL(atmel_tc_alloc);

/**
 * atmel_tc_free - release a specified TC block
 * @tc: Timer/counter block that was returned by atmel_tc_alloc()
 *
 * This reverses the effect of atmel_tc_alloc(), invalidating the resource
 * returned by that routine and making the TC available to other drivers.
 */
void atmel_tc_free(struct atmel_tc *tc)
{
	spin_lock(&tc_list_lock);
	if (tc->allocated)
		tc->allocated = false;
	spin_unlock(&tc_list_lock);
}
EXPORT_SYMBOL_GPL(atmel_tc_free);

#if defined(CONFIG_OF)
static struct atmel_tcb_config tcb_rm9200_config = {
	.counter_width = 16,
};

static struct atmel_tcb_config tcb_sam9x5_config = {
	.counter_width = 32,
};

static const struct of_device_id atmel_tcb_dt_ids[] = {
	{
		.compatible = "atmel,at91rm9200-tcb",
		.data = &tcb_rm9200_config,
	}, {
		.compatible = "atmel,at91sam9x5-tcb",
		.data = &tcb_sam9x5_config,
	}, {
		/* sentinel */
	}
};

MODULE_DEVICE_TABLE(of, atmel_tcb_dt_ids);
#endif

static int __init tc_probe(struct platform_device *pdev)
{
	struct atmel_tc *tc;
	struct clk	*clk;
	int		irq;
	struct resource	*r;
	unsigned int	i;

	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
		return -EINVAL;

	tc = devm_kzalloc(&pdev->dev, sizeof(struct atmel_tc), GFP_KERNEL);
	if (!tc)
		return -ENOMEM;

	tc->pdev = pdev;

	clk = devm_clk_get(&pdev->dev, "t0_clk");
	if (IS_ERR(clk))
		return PTR_ERR(clk);

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	tc->regs = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(tc->regs))
		return PTR_ERR(tc->regs);

	/* Now take SoC information if available */
	if (pdev->dev.of_node) {
		const struct of_device_id *match;
		match = of_match_node(atmel_tcb_dt_ids, pdev->dev.of_node);
		if (match)
			tc->tcb_config = match->data;

		tc->id = of_alias_get_id(tc->pdev->dev.of_node, "tcb");
	} else {
		tc->id = pdev->id;
	}

	tc->clk[0] = clk;
	tc->clk[1] = devm_clk_get(&pdev->dev, "t1_clk");
	if (IS_ERR(tc->clk[1]))
		tc->clk[1] = clk;
	tc->clk[2] = devm_clk_get(&pdev->dev, "t2_clk");
	if (IS_ERR(tc->clk[2]))
		tc->clk[2] = clk;

	tc->irq[0] = irq;
	tc->irq[1] = platform_get_irq(pdev, 1);
	if (tc->irq[1] < 0)
		tc->irq[1] = irq;
	tc->irq[2] = platform_get_irq(pdev, 2);
	if (tc->irq[2] < 0)
		tc->irq[2] = irq;

	for (i = 0; i < 3; i++)
		writel(ATMEL_TC_ALL_IRQ, tc->regs + ATMEL_TC_REG(i, IDR));

	spin_lock(&tc_list_lock);
	list_add_tail(&tc->node, &tc_list);
	spin_unlock(&tc_list_lock);

	platform_set_drvdata(pdev, tc);

	return 0;
}

static void tc_shutdown(struct platform_device *pdev)
{
	int i;
	struct atmel_tc *tc = platform_get_drvdata(pdev);

	for (i = 0; i < 3; i++)
		writel(ATMEL_TC_ALL_IRQ, tc->regs + ATMEL_TC_REG(i, IDR));
}

static struct platform_driver tc_driver = {
	.driver = {
		.name	= "atmel_tcb",
		.of_match_table	= of_match_ptr(atmel_tcb_dt_ids),
	},
	.shutdown = tc_shutdown,
};

static int __init tc_init(void)
{
	return platform_driver_probe(&tc_driver, tc_probe);
}
arch_initcall(tc_init);