[ARM] tegra: add PWM driver
add support for the pulse-width-modulation APIs using the tegra 2 internal PWM controllers Change-Id: If313301aaebab01f08edbe120060537e6917ea4b Signed-off-by: Gary King <gking@nvidia.com>
This commit is contained in:
Gary King
Colin Cross
parent
c45b3a9057
commit
e98e2b459a
3 changed files with 300 additions and 0 deletions
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@ -60,6 +60,12 @@ config TEGRA_SYSTEM_DMA
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Adds system DMA functionality for NVIDIA Tegra SoCs, used by
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several Tegra device drivers
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config TEGRA_PWM
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tristate "Enable PWM driver"
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select HAVE_PWM
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help
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Enable support for the Tegra PWM controller(s).
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endif
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config TEGRA_IOVMM_GART
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@ -13,6 +13,7 @@ obj-y += fuse.o
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obj-y += tegra_i2s_audio.o
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obj-$(CONFIG_USB_SUPPORT) += usb_phy.o
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obj-$(CONFIG_FIQ) += fiq.o
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obj-$(CONFIG_TEGRA_PWM) += pwm.o
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obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += clock.o
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obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += tegra2_clocks.o
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293
arch/arm/mach-tegra/pwm.c
Normal file
293
arch/arm/mach-tegra/pwm.c
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@ -0,0 +1,293 @@
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/*
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* arch/arm/mach-tegra/pwm.c
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*
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* Tegra pulse-width-modulation controller driver
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*
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* Copyright (c) 2010, NVIDIA Corporation.
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* Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/pwm.h>
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#include <linux/slab.h>
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#define PWM_ENABLE (1 << 31)
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#define PWM_DUTY_WIDTH 8
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#define PWM_DUTY_SHIFT 16
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#define PWM_SCALE_WIDTH 13
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#define PWM_SCALE_SHIFT 0
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struct pwm_device {
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struct list_head node;
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struct platform_device *pdev;
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const char *label;
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struct clk *clk;
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int clk_enb;
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void __iomem *mmio_base;
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unsigned int in_use;
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unsigned int id;
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};
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static DEFINE_MUTEX(pwm_lock);
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static LIST_HEAD(pwm_list);
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static inline int pwm_writel(struct pwm_device *pwm, unsigned long val)
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{
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int rc;
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rc = clk_enable(pwm->clk);
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if (WARN_ON(rc))
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return rc;
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writel(val, pwm->mmio_base);
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clk_disable(pwm->clk);
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return 0;
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}
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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unsigned long long c;
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unsigned long rate, hz;
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u32 val = 0;
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/* convert from duty_ns / period_ns to a fixed number of duty
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* ticks per (1 << PWM_DUTY_WIDTH) cycles. */
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c = duty_ns * ((1 << PWM_DUTY_WIDTH) - 1);
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do_div(c, period_ns);
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val = (u32)c << PWM_DUTY_SHIFT;
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/* compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
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* cycles at the PWM clock rate will take period_ns nanoseconds. */
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rate = clk_get_rate(pwm->clk) >> PWM_DUTY_WIDTH;
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hz = 1000000000ul / period_ns;
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rate = (rate + (hz / 2)) / hz;
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if (rate >> PWM_SCALE_WIDTH)
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return -EINVAL;
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val |= (rate << PWM_SCALE_SHIFT);
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/* the struct clk may be shared across multiple PWM devices, so
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* only enable the PWM if this device has been enabled */
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if (pwm->clk_enb)
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val |= PWM_ENABLE;
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return pwm_writel(pwm, val);
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}
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EXPORT_SYMBOL(pwm_config);
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int pwm_enable(struct pwm_device *pwm)
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{
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int rc = 0;
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mutex_lock(&pwm_lock);
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if (!pwm->clk_enb) {
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rc = clk_enable(pwm->clk);
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if (!rc) {
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u32 val = readl(pwm->mmio_base);
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writel(val | PWM_ENABLE, pwm->mmio_base);
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pwm->clk_enb = 1;
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}
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}
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mutex_unlock(&pwm_lock);
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return rc;
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}
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EXPORT_SYMBOL(pwm_enable);
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void pwm_disable(struct pwm_device *pwm)
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{
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mutex_lock(&pwm_lock);
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if (pwm->clk_enb) {
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u32 val = readl(pwm->mmio_base);
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writel(val & ~PWM_ENABLE, pwm->mmio_base);
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clk_disable(pwm->clk);
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pwm->clk_enb = 0;
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} else
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dev_warn(&pwm->pdev->dev, "%s called on disabled PWM\n",
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__func__);
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mutex_unlock(&pwm_lock);
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}
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EXPORT_SYMBOL(pwm_disable);
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struct pwm_device *pwm_request(int pwm_id, const char *label)
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{
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struct pwm_device *pwm;
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int found = 0;
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mutex_lock(&pwm_lock);
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list_for_each_entry(pwm, &pwm_list, node) {
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if (pwm->id == pwm_id) {
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found = 1;
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break;
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}
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}
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if (found) {
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if (!pwm->in_use) {
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pwm->in_use = 1;
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pwm->label = label;
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} else
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pwm = ERR_PTR(-EBUSY);
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} else
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pwm = ERR_PTR(-ENOENT);
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mutex_unlock(&pwm_lock);
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return pwm;
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}
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EXPORT_SYMBOL(pwm_request);
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void pwm_free(struct pwm_device *pwm)
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{
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mutex_lock(&pwm_lock);
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if (pwm->in_use) {
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pwm->in_use = 0;
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pwm->label = NULL;
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} else
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dev_warn(&pwm->pdev->dev, "PWM device already freed\n");
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mutex_unlock(&pwm_lock);
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}
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EXPORT_SYMBOL(pwm_free);
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static int tegra_pwm_probe(struct platform_device *pdev)
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{
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struct pwm_device *pwm;
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struct resource *r;
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int ret;
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pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
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if (!pwm) {
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dev_err(&pdev->dev, "failed to allocate memory\n");
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return -ENOMEM;
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}
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pwm->clk = clk_get(&pdev->dev, NULL);
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if (IS_ERR(pwm->clk)) {
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ret = PTR_ERR(pwm->clk);
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goto err_free;
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}
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pwm->clk_enb = 0;
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pwm->in_use = 0;
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pwm->id = pdev->id;
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pwm->pdev = pdev;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!r) {
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dev_err(&pdev->dev, "no memory resources defined\n");
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ret = -ENODEV;
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goto err_put_clk;
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}
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r = request_mem_region(r->start, resource_size(r), pdev->name);
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if (!r) {
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dev_err(&pdev->dev, "failed to request memory\n");
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ret = -EBUSY;
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goto err_put_clk;
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}
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pwm->mmio_base = ioremap(r->start, resource_size(r));
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if (!pwm->mmio_base) {
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dev_err(&pdev->dev, "failed to ioremap() region\n");
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ret = -ENODEV;
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goto err_free_mem;
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}
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platform_set_drvdata(pdev, pwm);
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mutex_lock(&pwm_lock);
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list_add_tail(&pwm->node, &pwm_list);
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mutex_unlock(&pwm_lock);
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return 0;
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err_free_mem:
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release_mem_region(r->start, resource_size(r));
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err_put_clk:
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clk_put(pwm->clk);
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err_free:
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kfree(pwm);
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return ret;
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}
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static int __devexit tegra_pwm_remove(struct platform_device *pdev)
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{
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struct pwm_device *pwm = platform_get_drvdata(pdev);
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struct resource *r;
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int rc;
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if (WARN_ON(!pwm))
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return -ENODEV;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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mutex_lock(&pwm_lock);
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if (pwm->in_use) {
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mutex_unlock(&pwm_lock);
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return -EBUSY;
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}
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list_del(&pwm->node);
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mutex_unlock(&pwm_lock);
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rc = pwm_writel(pwm, 0);
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iounmap(pwm->mmio_base);
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release_mem_region(r->start, resource_size(r));
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if (pwm->clk_enb)
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clk_disable(pwm->clk);
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clk_put(pwm->clk);
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kfree(pwm);
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return rc;
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}
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static struct platform_driver tegra_pwm_driver = {
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.driver = {
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.name = "tegra_pwm",
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},
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.probe = tegra_pwm_probe,
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.remove = __devexit_p(tegra_pwm_remove),
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};
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static int __init tegra_pwm_init(void)
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{
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return platform_driver_register(&tegra_pwm_driver);
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}
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subsys_initcall(tegra_pwm_init);
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static void __exit tegra_pwm_exit(void)
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{
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platform_driver_unregister(&tegra_pwm_driver);
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}
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module_exit(tegra_pwm_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("NVIDIA Corporation");
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