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path: root/drivers/pwm/pwm-vt8500.c
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Diffstat (limited to 'drivers/pwm/pwm-vt8500.c')
-rw-r--r--drivers/pwm/pwm-vt8500.c276
1 files changed, 276 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
new file mode 100644
index 000000000..cdb58fd46
--- /dev/null
+++ b/drivers/pwm/pwm-vt8500.c
@@ -0,0 +1,276 @@
+/*
+ * drivers/pwm/pwm-vt8500.c
+ *
+ * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
+ * 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 <linux/clk.h>
+
+#include <asm/div64.h>
+
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+
+/*
+ * SoC architecture allocates register space for 4 PWMs but only
+ * 2 are currently implemented.
+ */
+#define VT8500_NR_PWMS 2
+
+#define REG_CTRL(pwm) (((pwm) << 4) + 0x00)
+#define REG_SCALAR(pwm) (((pwm) << 4) + 0x04)
+#define REG_PERIOD(pwm) (((pwm) << 4) + 0x08)
+#define REG_DUTY(pwm) (((pwm) << 4) + 0x0C)
+#define REG_STATUS 0x40
+
+#define CTRL_ENABLE BIT(0)
+#define CTRL_INVERT BIT(1)
+#define CTRL_AUTOLOAD BIT(2)
+#define CTRL_STOP_IMM BIT(3)
+#define CTRL_LOAD_PRESCALE BIT(4)
+#define CTRL_LOAD_PERIOD BIT(5)
+
+#define STATUS_CTRL_UPDATE BIT(0)
+#define STATUS_SCALAR_UPDATE BIT(1)
+#define STATUS_PERIOD_UPDATE BIT(2)
+#define STATUS_DUTY_UPDATE BIT(3)
+#define STATUS_ALL_UPDATE 0x0F
+
+struct vt8500_chip {
+ struct pwm_chip chip;
+ void __iomem *base;
+ struct clk *clk;
+};
+
+#define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip)
+
+#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
+static inline void pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
+{
+ int loops = msecs_to_loops(10);
+ u32 mask = bitmask << (nr << 8);
+
+ while ((readl(vt8500->base + REG_STATUS) & mask) && --loops)
+ cpu_relax();
+
+ if (unlikely(!loops))
+ dev_warn(vt8500->chip.dev, "Waiting for status bits 0x%x to clear timed out\n",
+ mask);
+}
+
+static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
+ unsigned long long c;
+ unsigned long period_cycles, prescale, pv, dc;
+ int err;
+ u32 val;
+
+ err = clk_enable(vt8500->clk);
+ if (err < 0) {
+ dev_err(chip->dev, "failed to enable clock\n");
+ return err;
+ }
+
+ c = clk_get_rate(vt8500->clk);
+ 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) {
+ clk_disable(vt8500->clk);
+ return -EINVAL;
+ }
+
+ c = (unsigned long long)pv * duty_ns;
+ do_div(c, period_ns);
+ dc = c;
+
+ writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
+ pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);
+
+ writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm));
+ pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE);
+
+ writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm));
+ pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE);
+
+ val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
+ val |= CTRL_AUTOLOAD;
+ writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
+ pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+
+ clk_disable(vt8500->clk);
+ return 0;
+}
+
+static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
+ int err;
+ u32 val;
+
+ err = clk_enable(vt8500->clk);
+ if (err < 0) {
+ dev_err(chip->dev, "failed to enable clock\n");
+ return err;
+ }
+
+ val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
+ val |= CTRL_ENABLE;
+ writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
+ pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+
+ return 0;
+}
+
+static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
+ u32 val;
+
+ val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
+ val &= ~CTRL_ENABLE;
+ writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
+ pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+
+ clk_disable(vt8500->clk);
+}
+
+static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
+ u32 val;
+
+ val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
+
+ if (polarity == PWM_POLARITY_INVERSED)
+ val |= CTRL_INVERT;
+ else
+ val &= ~CTRL_INVERT;
+
+ writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
+ pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+
+ return 0;
+}
+
+static struct pwm_ops vt8500_pwm_ops = {
+ .enable = vt8500_pwm_enable,
+ .disable = vt8500_pwm_disable,
+ .config = vt8500_pwm_config,
+ .set_polarity = vt8500_pwm_set_polarity,
+ .owner = THIS_MODULE,
+};
+
+static const struct of_device_id vt8500_pwm_dt_ids[] = {
+ { .compatible = "via,vt8500-pwm", },
+ { /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);
+
+static int vt8500_pwm_probe(struct platform_device *pdev)
+{
+ struct vt8500_chip *chip;
+ struct resource *r;
+ struct device_node *np = pdev->dev.of_node;
+ int ret;
+
+ if (!np) {
+ dev_err(&pdev->dev, "invalid devicetree node\n");
+ return -EINVAL;
+ }
+
+ chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+ if (chip == NULL)
+ return -ENOMEM;
+
+ chip->chip.dev = &pdev->dev;
+ chip->chip.ops = &vt8500_pwm_ops;
+ chip->chip.of_xlate = of_pwm_xlate_with_flags;
+ chip->chip.of_pwm_n_cells = 3;
+ chip->chip.base = -1;
+ chip->chip.npwm = VT8500_NR_PWMS;
+
+ chip->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(chip->clk)) {
+ dev_err(&pdev->dev, "clock source not specified\n");
+ return PTR_ERR(chip->clk);
+ }
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ chip->base = devm_ioremap_resource(&pdev->dev, r);
+ if (IS_ERR(chip->base))
+ return PTR_ERR(chip->base);
+
+ ret = clk_prepare(chip->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to prepare clock\n");
+ return ret;
+ }
+
+ ret = pwmchip_add(&chip->chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to add PWM chip\n");
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, chip);
+ return ret;
+}
+
+static int vt8500_pwm_remove(struct platform_device *pdev)
+{
+ struct vt8500_chip *chip;
+
+ chip = platform_get_drvdata(pdev);
+ if (chip == NULL)
+ return -ENODEV;
+
+ clk_unprepare(chip->clk);
+
+ return pwmchip_remove(&chip->chip);
+}
+
+static struct platform_driver vt8500_pwm_driver = {
+ .probe = vt8500_pwm_probe,
+ .remove = vt8500_pwm_remove,
+ .driver = {
+ .name = "vt8500-pwm",
+ .of_match_table = vt8500_pwm_dt_ids,
+ },
+};
+module_platform_driver(vt8500_pwm_driver);
+
+MODULE_DESCRIPTION("VT8500 PWM Driver");
+MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
+MODULE_LICENSE("GPL v2");
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-17 11:11:28 +0000