diff options
Diffstat (limited to 'drivers/pwm/pwm-dwc-core.c')
| -rw-r--r-- | drivers/pwm/pwm-dwc-core.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-dwc-core.c b/drivers/pwm/pwm-dwc-core.c new file mode 100644 index 000000000000..ea63dd741f5c --- /dev/null +++ b/drivers/pwm/pwm-dwc-core.c @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * DesignWare PWM Controller driver core + * + * Copyright (C) 2018-2020 Intel Corporation + * + * Author: Felipe Balbi (Intel) + * Author: Jarkko Nikula <jarkko.nikula@linux.intel.com> + * Author: Raymond Tan <raymond.tan@intel.com> + */ + +#define DEFAULT_SYMBOL_NAMESPACE dwc_pwm + +#include <linux/bitops.h> +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/pci.h> +#include <linux/pm_runtime.h> +#include <linux/pwm.h> + +#include "pwm-dwc.h" + +static void __dwc_pwm_set_enable(struct dwc_pwm *dwc, int pwm, int enabled) +{ + u32 reg; + + reg = dwc_pwm_readl(dwc, DWC_TIM_CTRL(pwm)); + + if (enabled) + reg |= DWC_TIM_CTRL_EN; + else + reg &= ~DWC_TIM_CTRL_EN; + + dwc_pwm_writel(dwc, reg, DWC_TIM_CTRL(pwm)); +} + +static int __dwc_pwm_configure_timer(struct dwc_pwm *dwc, + struct pwm_device *pwm, + const struct pwm_state *state) +{ + u64 tmp; + u32 ctrl; + u32 high; + u32 low; + + /* + * Calculate width of low and high period in terms of input clock + * periods and check are the result within HW limits between 1 and + * 2^32 periods. + */ + tmp = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, dwc->clk_ns); + if (tmp < 1 || tmp > (1ULL << 32)) + return -ERANGE; + low = tmp - 1; + + tmp = DIV_ROUND_CLOSEST_ULL(state->period - state->duty_cycle, + dwc->clk_ns); + if (tmp < 1 || tmp > (1ULL << 32)) + return -ERANGE; + high = tmp - 1; + + /* + * Specification says timer usage flow is to disable timer, then + * program it followed by enable. It also says Load Count is loaded + * into timer after it is enabled - either after a disable or + * a reset. Based on measurements it happens also without disable + * whenever Load Count is updated. But follow the specification. + */ + __dwc_pwm_set_enable(dwc, pwm->hwpwm, false); + + /* + * Write Load Count and Load Count 2 registers. Former defines the + * width of low period and latter the width of high period in terms + * multiple of input clock periods: + * Width = ((Count + 1) * input clock period). + */ + dwc_pwm_writel(dwc, low, DWC_TIM_LD_CNT(pwm->hwpwm)); + dwc_pwm_writel(dwc, high, DWC_TIM_LD_CNT2(pwm->hwpwm)); + + /* + * Set user-defined mode, timer reloads from Load Count registers + * when it counts down to 0. + * Set PWM mode, it makes output to toggle and width of low and high + * periods are set by Load Count registers. + */ + ctrl = DWC_TIM_CTRL_MODE_USER | DWC_TIM_CTRL_PWM; + dwc_pwm_writel(dwc, ctrl, DWC_TIM_CTRL(pwm->hwpwm)); + + /* + * Enable timer. Output starts from low period. + */ + __dwc_pwm_set_enable(dwc, pwm->hwpwm, state->enabled); + + return 0; +} + +static int dwc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct dwc_pwm *dwc = to_dwc_pwm(chip); + + if (state->polarity != PWM_POLARITY_INVERSED) + return -EINVAL; + + if (state->enabled) { + if (!pwm->state.enabled) + pm_runtime_get_sync(chip->dev); + return __dwc_pwm_configure_timer(dwc, pwm, state); + } else { + if (pwm->state.enabled) { + __dwc_pwm_set_enable(dwc, pwm->hwpwm, false); + pm_runtime_put_sync(chip->dev); + } + } + + return 0; +} + +static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + struct dwc_pwm *dwc = to_dwc_pwm(chip); + u64 duty, period; + u32 ctrl, ld, ld2; + + pm_runtime_get_sync(chip->dev); + + ctrl = dwc_pwm_readl(dwc, DWC_TIM_CTRL(pwm->hwpwm)); + ld = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(pwm->hwpwm)); + ld2 = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(pwm->hwpwm)); + + state->enabled = !!(ctrl & DWC_TIM_CTRL_EN); + + /* + * If we're not in PWM, technically the output is a 50-50 + * based on the timer load-count only. + */ + if (ctrl & DWC_TIM_CTRL_PWM) { + duty = (ld + 1) * dwc->clk_ns; + period = (ld2 + 1) * dwc->clk_ns; + period += duty; + } else { + duty = (ld + 1) * dwc->clk_ns; + period = duty * 2; + } + + state->polarity = PWM_POLARITY_INVERSED; + state->period = period; + state->duty_cycle = duty; + + pm_runtime_put_sync(chip->dev); + + return 0; +} + +static const struct pwm_ops dwc_pwm_ops = { + .apply = dwc_pwm_apply, + .get_state = dwc_pwm_get_state, +}; + +struct dwc_pwm *dwc_pwm_alloc(struct device *dev) +{ + struct dwc_pwm *dwc; + + dwc = devm_kzalloc(dev, sizeof(*dwc), GFP_KERNEL); + if (!dwc) + return NULL; + + dwc->clk_ns = 10; + dwc->chip.dev = dev; + dwc->chip.ops = &dwc_pwm_ops; + dwc->chip.npwm = DWC_TIMERS_TOTAL; + + dev_set_drvdata(dev, dwc); + return dwc; +} +EXPORT_SYMBOL_GPL(dwc_pwm_alloc); + +MODULE_AUTHOR("Felipe Balbi (Intel)"); +MODULE_AUTHOR("Jarkko Nikula <jarkko.nikula@linux.intel.com>"); +MODULE_AUTHOR("Raymond Tan <raymond.tan@intel.com>"); +MODULE_DESCRIPTION("DesignWare PWM Controller"); +MODULE_LICENSE("GPL"); |