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>
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");