ARM: 6597/1: Add basic architecture support for VIA/WonderMedia 85xx SoC's

This adds support for the family of Systems-on-Chip produced initially
by VIA and now its subsidiary WonderMedia that have recently become
widespread in lower-end Chinese ARM-based tablets and netbooks.

Support is included for both VT8500 and WM8505, selectable by a
configuration switch at kernel build time.

Included are basic machine initialization files, register and
interrupt definitions, support for the on-chip interrupt controller,
high-precision OS timer, GPIO lines, necessary macros for early debug,
pulse-width-modulated outputs control, as well as platform device
configurations for the specific drivers implemented elsewhere.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 265 insertions, 0 deletions

diff --git a/arch/arm/mach-vt8500/pwm.c b/arch/arm/mach-vt8500/pwm.c
new file mode 100644
index 0000000..8ad825e
--- /dev/null
+++ b/arch/arm/mach-vt8500/pwm.c
@@ -0,0 +1,265 @@
+/*
+ * arch/arm/mach-vt8500/pwm.c
+ *
+ *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/pwm.h>
+#include <linux/delay.h>
+
+#include <asm/div64.h>
+
+#define VT8500_NR_PWMS 4
+
+static DEFINE_MUTEX(pwm_lock);
+static LIST_HEAD(pwm_list);
+
+struct pwm_device {
+	struct list_head	node;
+	struct platform_device	*pdev;
+
+	const char	*label;
+
+	void __iomem	*regbase;
+
+	unsigned int	use_count;
+	unsigned int	pwm_id;
+};
+
+#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
+static inline void pwm_busy_wait(void __iomem *reg, u8 bitmask)
+{
+	int loops = msecs_to_loops(10);
+	while ((readb(reg) & bitmask) && --loops)
+		cpu_relax();
+
+	if (unlikely(!loops))
+		pr_warning("Waiting for status bits 0x%x to clear timed out\n",
+			   bitmask);
+}
+
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+	unsigned long long c;
+	unsigned long period_cycles, prescale, pv, dc;
+
+	if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
+		return -EINVAL;
+
+	c = 25000000/2; /* wild guess --- need to implement clocks */
+	c = c * period_ns;
+	do_div(c, 1000000000);
+	period_cycles = c;
+
+	if (period_cycles < 1)
+		period_cycles = 1;
+	prescale = (period_cycles - 1) / 4096;
+	pv = period_cycles / (prescale + 1) - 1;
+	if (pv > 4095)
+		pv = 4095;
+
+	if (prescale > 1023)
+		return -EINVAL;
+
+	c = (unsigned long long)pv * duty_ns;
+	do_div(c, period_ns);
+	dc = c;
+
+	pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 1));
+	writel(prescale, pwm->regbase + 0x4 + (pwm->pwm_id << 4));
+
+	pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 2));
+	writel(pv, pwm->regbase + 0x8 + (pwm->pwm_id << 4));
+
+	pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 3));
+	writel(dc, pwm->regbase + 0xc + (pwm->pwm_id << 4));
+
+	return 0;
+}
+EXPORT_SYMBOL(pwm_config);
+
+int pwm_enable(struct pwm_device *pwm)
+{
+	pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 0));
+	writel(5, pwm->regbase + (pwm->pwm_id << 4));
+	return 0;
+}
+EXPORT_SYMBOL(pwm_enable);
+
+void pwm_disable(struct pwm_device *pwm)
+{
+	pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 0));
+	writel(0, pwm->regbase + (pwm->pwm_id << 4));
+}
+EXPORT_SYMBOL(pwm_disable);
+
+struct pwm_device *pwm_request(int pwm_id, const char *label)
+{
+	struct pwm_device *pwm;
+	int found = 0;
+
+	mutex_lock(&pwm_lock);
+
+	list_for_each_entry(pwm, &pwm_list, node) {
+		if (pwm->pwm_id == pwm_id) {
+			found = 1;
+			break;
+		}
+	}
+
+	if (found) {
+		if (pwm->use_count == 0) {
+			pwm->use_count++;
+			pwm->label = label;
+		} else {
+			pwm = ERR_PTR(-EBUSY);
+		}
+	} else {
+		pwm = ERR_PTR(-ENOENT);
+	}
+
+	mutex_unlock(&pwm_lock);
+	return pwm;
+}
+EXPORT_SYMBOL(pwm_request);
+
+void pwm_free(struct pwm_device *pwm)
+{
+	mutex_lock(&pwm_lock);
+
+	if (pwm->use_count) {
+		pwm->use_count--;
+		pwm->label = NULL;
+	} else {
+		pr_warning("PWM device already freed\n");
+	}
+
+	mutex_unlock(&pwm_lock);
+}
+EXPORT_SYMBOL(pwm_free);
+
+static inline void __add_pwm(struct pwm_device *pwm)
+{
+	mutex_lock(&pwm_lock);
+	list_add_tail(&pwm->node, &pwm_list);
+	mutex_unlock(&pwm_lock);
+}
+
+static int __devinit pwm_probe(struct platform_device *pdev)
+{
+	struct pwm_device *pwms;
+	struct resource *r;
+	int ret = 0;
+	int i;
+
+	pwms = kzalloc(sizeof(struct pwm_device) * VT8500_NR_PWMS, GFP_KERNEL);
+	if (pwms == NULL) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < VT8500_NR_PWMS; i++) {
+		pwms[i].use_count = 0;
+		pwms[i].pwm_id = i;
+		pwms[i].pdev = pdev;
+	}
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		dev_err(&pdev->dev, "no memory resource defined\n");
+		ret = -ENODEV;
+		goto err_free;
+	}
+
+	r = request_mem_region(r->start, resource_size(r), pdev->name);
+	if (r == NULL) {
+		dev_err(&pdev->dev, "failed to request memory resource\n");
+		ret = -EBUSY;
+		goto err_free;
+	}
+
+	pwms[0].regbase = ioremap(r->start, resource_size(r));
+	if (pwms[0].regbase == NULL) {
+		dev_err(&pdev->dev, "failed to ioremap() registers\n");
+		ret = -ENODEV;
+		goto err_free_mem;
+	}
+
+	for (i = 1; i < VT8500_NR_PWMS; i++)
+		pwms[i].regbase = pwms[0].regbase;
+
+	for (i = 0; i < VT8500_NR_PWMS; i++)
+		__add_pwm(&pwms[i]);
+
+	platform_set_drvdata(pdev, pwms);
+	return 0;
+
+err_free_mem:
+	release_mem_region(r->start, resource_size(r));
+err_free:
+	kfree(pwms);
+	return ret;
+}
+
+static int __devexit pwm_remove(struct platform_device *pdev)
+{
+	struct pwm_device *pwms;
+	struct resource *r;
+	int i;
+
+	pwms = platform_get_drvdata(pdev);
+	if (pwms == NULL)
+		return -ENODEV;
+
+	mutex_lock(&pwm_lock);
+
+	for (i = 0; i < VT8500_NR_PWMS; i++)
+		list_del(&pwms[i].node);
+	mutex_unlock(&pwm_lock);
+
+	iounmap(pwms[0].regbase);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(r->start, resource_size(r));
+
+	kfree(pwms);
+	return 0;
+}
+
+static struct platform_driver pwm_driver = {
+	.driver		= {
+		.name	= "vt8500-pwm",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= pwm_probe,
+	.remove		= __devexit_p(pwm_remove),
+};
+
+static int __init pwm_init(void)
+{
+	return platform_driver_register(&pwm_driver);
+}
+arch_initcall(pwm_init);
+
+static void __exit pwm_exit(void)
+{
+	platform_driver_unregister(&pwm_driver);
+}
+module_exit(pwm_exit);
+
+MODULE_LICENSE("GPL");