// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2019 Spreadtrum Communications Inc. */ #include <linux/clk.h> #include <linux/err.h> #include <linux/io.h> #include <linux/math64.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/pwm.h> #define SPRD_PWM_PRESCALE 0x0 #define SPRD_PWM_MOD 0x4 #define SPRD_PWM_DUTY 0x8 #define SPRD_PWM_ENABLE 0x18 #define SPRD_PWM_MOD_MAX GENMASK(7, 0) #define SPRD_PWM_DUTY_MSK GENMASK(15, 0) #define SPRD_PWM_PRESCALE_MSK GENMASK(7, 0) #define SPRD_PWM_ENABLE_BIT BIT(0) #define SPRD_PWM_CHN_NUM 4 #define SPRD_PWM_REGS_SHIFT 5 #define SPRD_PWM_CHN_CLKS_NUM 2 #define SPRD_PWM_CHN_OUTPUT_CLK 1 struct sprd_pwm_chn { struct clk_bulk_data clks[SPRD_PWM_CHN_CLKS_NUM]; u32 clk_rate; }; struct sprd_pwm_chip { void __iomem *base; struct device *dev; struct pwm_chip chip; int num_pwms; struct sprd_pwm_chn chn[SPRD_PWM_CHN_NUM]; }; /* * The list of clocks required by PWM channels, and each channel has 2 clocks: * enable clock and pwm clock. */ static const char * const sprd_pwm_clks[] = { "enable0", "pwm0", "enable1", "pwm1", "enable2", "pwm2", "enable3", "pwm3", }; static u32 sprd_pwm_read(struct sprd_pwm_chip *spc, u32 hwid, u32 reg) { u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT); return readl_relaxed(spc->base + offset); } static void sprd_pwm_write(struct sprd_pwm_chip *spc, u32 hwid, u32 reg, u32 val) { u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT); writel_relaxed(val, spc->base + offset); } static int sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { struct sprd_pwm_chip *spc = container_of(chip, struct sprd_pwm_chip, chip); struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm]; u32 val, duty, prescale; u64 tmp; int ret; /* * The clocks to PWM channel has to be enabled first before * reading to the registers. */ ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, chn->clks); if (ret) { dev_err(spc->dev, "failed to enable pwm%u clocks\n", pwm->hwpwm); return ret; } val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_ENABLE); if (val & SPRD_PWM_ENABLE_BIT) state->enabled = true; else state->enabled = false; /* * The hardware provides a counter that is feed by the source clock. * The period length is (PRESCALE + 1) * MOD counter steps. * The duty cycle length is (PRESCALE + 1) * DUTY counter steps. * Thus the period_ns and duty_ns calculation formula should be: * period_ns = NSEC_PER_SEC * (prescale + 1) * mod / clk_rate * duty_ns = NSEC_PER_SEC * (prescale + 1) * duty / clk_rate */ val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_PRESCALE); prescale = val & SPRD_PWM_PRESCALE_MSK; tmp = (prescale + 1) * NSEC_PER_SEC * SPRD_PWM_MOD_MAX; state->period = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate); val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_DUTY); duty = val & SPRD_PWM_DUTY_MSK; tmp = (prescale + 1) * NSEC_PER_SEC * duty; state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate); state->polarity = PWM_POLARITY_NORMAL; /* Disable PWM clocks if the PWM channel is not in enable state. */ if (!state->enabled) clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks); return 0; } static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm, int duty_ns, int period_ns) { struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm]; u32 prescale, duty; u64 tmp; /* * The hardware provides a counter that is feed by the source clock. * The period length is (PRESCALE + 1) * MOD counter steps. * The duty cycle length is (PRESCALE + 1) * DUTY counter steps. * * To keep the maths simple we're always using MOD = SPRD_PWM_MOD_MAX. * The value for PRESCALE is selected such that the resulting period * gets the maximal length not bigger than the requested one with the * given settings (MOD = SPRD_PWM_MOD_MAX and input clock). */ duty = duty_ns * SPRD_PWM_MOD_MAX / period_ns; tmp = (u64)chn->clk_rate * period_ns; do_div(tmp, NSEC_PER_SEC); prescale = DIV_ROUND_CLOSEST_ULL(tmp, SPRD_PWM_MOD_MAX) - 1; if (prescale > SPRD_PWM_PRESCALE_MSK) prescale = SPRD_PWM_PRESCALE_MSK; /* * Note: Writing DUTY triggers the hardware to actually apply the * values written to MOD and DUTY to the output, so must keep writing * DUTY last. * * The hardware can ensures that current running period is completed * before changing a new configuration to avoid mixed settings. */ sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_PRESCALE, prescale); sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_MOD, SPRD_PWM_MOD_MAX); sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_DUTY, duty); return 0; } static int sprd_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { struct sprd_pwm_chip *spc = container_of(chip, struct sprd_pwm_chip, chip); struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm]; struct pwm_state *cstate = &pwm->state; int ret; if (state->polarity != PWM_POLARITY_NORMAL) return -EINVAL; if (state->enabled) { if (!cstate->enabled) { /* * The clocks to PWM channel has to be enabled first * before writing to the registers. */ ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, chn->clks); if (ret) { dev_err(spc->dev, "failed to enable pwm%u clocks\n", pwm->hwpwm); return ret; } } ret = sprd_pwm_config(spc, pwm, state->duty_cycle, state->period); if (ret) return ret; sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 1); } else if (cstate->enabled) { /* * Note: After setting SPRD_PWM_ENABLE to zero, the controller * will not wait for current period to be completed, instead it * will stop the PWM channel immediately. */ sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 0); clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks); } return 0; } static const struct pwm_ops sprd_pwm_ops = { .apply = sprd_pwm_apply, .get_state = sprd_pwm_get_state, .owner = THIS_MODULE, }; static int sprd_pwm_clk_init(struct sprd_pwm_chip *spc) { struct clk *clk_pwm; int ret, i; for (i = 0; i < SPRD_PWM_CHN_NUM; i++) { struct sprd_pwm_chn *chn = &spc->chn[i]; int j; for (j = 0; j < SPRD_PWM_CHN_CLKS_NUM; ++j) chn->clks[j].id = sprd_pwm_clks[i * SPRD_PWM_CHN_CLKS_NUM + j]; ret = devm_clk_bulk_get(spc->dev, SPRD_PWM_CHN_CLKS_NUM, chn->clks); if (ret) { if (ret == -ENOENT) break; return dev_err_probe(spc->dev, ret, "failed to get channel clocks\n"); } clk_pwm = chn->clks[SPRD_PWM_CHN_OUTPUT_CLK].clk; chn->clk_rate = clk_get_rate(clk_pwm); } if (!i) { dev_err(spc->dev, "no available PWM channels\n"); return -ENODEV; } spc->num_pwms = i; return 0; } static int sprd_pwm_probe(struct platform_device *pdev) { struct sprd_pwm_chip *spc; int ret; spc = devm_kzalloc(&pdev->dev, sizeof(*spc), GFP_KERNEL); if (!spc) return -ENOMEM; spc->base = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(spc->base)) return PTR_ERR(spc->base); spc->dev = &pdev->dev; platform_set_drvdata(pdev, spc); ret = sprd_pwm_clk_init(spc); if (ret) return ret; spc->chip.dev = &pdev->dev; spc->chip.ops = &sprd_pwm_ops; spc->chip.npwm = spc->num_pwms; ret = pwmchip_add(&spc->chip); if (ret) dev_err(&pdev->dev, "failed to add PWM chip\n"); return ret; } static void sprd_pwm_remove(struct platform_device *pdev) { struct sprd_pwm_chip *spc = platform_get_drvdata(pdev); pwmchip_remove(&spc->chip); } static const struct of_device_id sprd_pwm_of_match[] = { { .compatible = "sprd,ums512-pwm", }, { }, }; MODULE_DEVICE_TABLE(of, sprd_pwm_of_match); static struct platform_driver sprd_pwm_driver = { .driver = { .name = "sprd-pwm", .of_match_table = sprd_pwm_of_match, }, .probe = sprd_pwm_probe, .remove_new = sprd_pwm_remove, }; module_platform_driver(sprd_pwm_driver); MODULE_DESCRIPTION("Spreadtrum PWM Driver"); MODULE_LICENSE("GPL v2");