atmel_tc library

Create <linux/atmel_tc.h> based on <asm-arm/arch-at91/at91-tc.h> and the
at91sam9263 and at32ap7000 datasheets.  Most AT91 and AT32 SOCs have one
or two of these TC blocks, which include three 16-bit timers that can be
interconnected in various ways.

These TC blocks can be used for external interfacing (such as PWM and
measurement), or used as somewhat quirky sixteen-bit timers.

Changes relative to the original version:
  * Drop unneeded inclusion of <linux/mutex.h>
  * Support an arbitrary number of TC blocks
  * Return a struct with information about a TC block from
    atmel_tc_alloc() instead of using a combination of return values
    and "out" parameters.
  * ioremap() the I/O registers on allocation
  * Look up clocks and irqs for all channels
  * Add "name" parameter to atmel_tc_alloc() and use this when
    requesting the iomem resource.
  * Check if the platform provided the necessary resources at probe()
    time instead of when the TCB is allocated.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

1 files changed, 161 insertions, 0 deletions

diff --git a/drivers/misc/atmel_tclib.c b/drivers/misc/atmel_tclib.c
new file mode 100644
index 000000000000..05dc8a31f280
--- /dev/null
+++ b/drivers/misc/atmel_tclib.c
@@ -0,0 +1,161 @@
+#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>
+
+/* Number of bytes to reserve for the iomem resource */
+#define ATMEL_TC_IOMEM_SIZE	256
+
+
+/*
+ * 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
+ * @name: name to be associated with the iomem resource
+ *
+ * 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, const char *name)
+{
+	struct atmel_tc		*tc;
+	struct platform_device	*pdev = NULL;
+	struct resource		*r;
+
+	spin_lock(&tc_list_lock);
+	list_for_each_entry(tc, &tc_list, node) {
+		if (tc->pdev->id == block) {
+			pdev = tc->pdev;
+			break;
+		}
+	}
+
+	if (!pdev || tc->iomem)
+		goto fail;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	r = request_mem_region(r->start, ATMEL_TC_IOMEM_SIZE, name);
+	if (!r)
+		goto fail;
+
+	tc->regs = ioremap(r->start, ATMEL_TC_IOMEM_SIZE);
+	if (!tc->regs)
+		goto fail_ioremap;
+
+	tc->iomem = r;
+
+out:
+	spin_unlock(&tc_list_lock);
+	return tc;
+
+fail_ioremap:
+	release_resource(r);
+fail:
+	tc = NULL;
+	goto out;
+}
+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(), unmapping the I/O
+ * registers, 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->regs) {
+		iounmap(tc->regs);
+		release_resource(tc->iomem);
+		tc->regs = NULL;
+		tc->iomem = NULL;
+	}
+	spin_unlock(&tc_list_lock);
+}
+EXPORT_SYMBOL_GPL(atmel_tc_free);
+
+static int __init tc_probe(struct platform_device *pdev)
+{
+	struct atmel_tc *tc;
+	struct clk	*clk;
+	int		irq;
+
+	if (!platform_get_resource(pdev, IORESOURCE_MEM, 0))
+		return -EINVAL;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return -EINVAL;
+
+	tc = kzalloc(sizeof(struct atmel_tc), GFP_KERNEL);
+	if (!tc)
+		return -ENOMEM;
+
+	tc->pdev = pdev;
+
+	clk = clk_get(&pdev->dev, "t0_clk");
+	if (IS_ERR(clk)) {
+		kfree(tc);
+		return -EINVAL;
+	}
+
+	tc->clk[0] = clk;
+	tc->clk[1] = clk_get(&pdev->dev, "t1_clk");
+	if (IS_ERR(tc->clk[1]))
+		tc->clk[1] = clk;
+	tc->clk[2] = 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;
+
+	spin_lock(&tc_list_lock);
+	list_add_tail(&tc->node, &tc_list);
+	spin_unlock(&tc_list_lock);
+
+	return 0;
+}
+
+static struct platform_driver tc_driver = {
+	.driver.name	= "atmel_tcb",
+};
+
+static int __init tc_init(void)
+{
+	return platform_driver_probe(&tc_driver, tc_probe);
+}
+arch_initcall(tc_init);