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https://github.com/brain-hackers/u-boot-brain
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173 lines
4.6 KiB
C
173 lines
4.6 KiB
C
![]() |
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2020 SiFive, Inc
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* For SiFive's PWM IP block documentation please refer Chapter 14 of
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* Reference Manual : https://static.dev.sifive.com/FU540-C000-v1.0.pdf
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*
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* Limitations:
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* - When changing both duty cycle and period, we cannot prevent in
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* software that the output might produce a period with mixed
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* settings (new period length and old duty cycle).
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* - The hardware cannot generate a 100% duty cycle.
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* - The hardware generates only inverted output.
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*/
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#include <common.h>
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#include <clk.h>
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#include <div64.h>
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#include <dm.h>
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#include <pwm.h>
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#include <regmap.h>
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#include <linux/io.h>
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#include <linux/log2.h>
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#include <linux/bitfield.h>
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/* PWMCFG fields */
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#define PWM_SIFIVE_PWMCFG_SCALE GENMASK(3, 0)
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#define PWM_SIFIVE_PWMCFG_STICKY BIT(8)
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#define PWM_SIFIVE_PWMCFG_ZERO_CMP BIT(9)
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#define PWM_SIFIVE_PWMCFG_DEGLITCH BIT(10)
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#define PWM_SIFIVE_PWMCFG_EN_ALWAYS BIT(12)
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#define PWM_SIFIVE_PWMCFG_EN_ONCE BIT(13)
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#define PWM_SIFIVE_PWMCFG_CENTER BIT(16)
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#define PWM_SIFIVE_PWMCFG_GANG BIT(24)
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#define PWM_SIFIVE_PWMCFG_IP BIT(28)
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/* PWM_SIFIVE_SIZE_PWMCMP is used to calculate offset for pwmcmpX registers */
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#define PWM_SIFIVE_SIZE_PWMCMP 4
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#define PWM_SIFIVE_CMPWIDTH 16
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DECLARE_GLOBAL_DATA_PTR;
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struct pwm_sifive_regs {
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unsigned long cfg;
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unsigned long cnt;
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unsigned long pwms;
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unsigned long cmp0;
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};
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struct pwm_sifive_data {
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struct pwm_sifive_regs regs;
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};
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struct pwm_sifive_priv {
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void __iomem *base;
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ulong freq;
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const struct pwm_sifive_data *data;
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};
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static int pwm_sifive_set_config(struct udevice *dev, uint channel,
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uint period_ns, uint duty_ns)
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{
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struct pwm_sifive_priv *priv = dev_get_priv(dev);
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const struct pwm_sifive_regs *regs = &priv->data->regs;
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unsigned long scale_pow;
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unsigned long long num;
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u32 scale, val = 0, frac;
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debug("%s: period_ns=%u, duty_ns=%u\n", __func__, period_ns, duty_ns);
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/*
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* The PWM unit is used with pwmzerocmp=0, so the only way to modify the
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* period length is using pwmscale which provides the number of bits the
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* counter is shifted before being feed to the comparators. A period
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* lasts (1 << (PWM_SIFIVE_CMPWIDTH + pwmscale)) clock ticks.
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* (1 << (PWM_SIFIVE_CMPWIDTH + scale)) * 10^9/rate = period
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*/
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scale_pow = lldiv((uint64_t)priv->freq * period_ns, 1000000000);
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scale = clamp(ilog2(scale_pow) - PWM_SIFIVE_CMPWIDTH, 0, 0xf);
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val |= FIELD_PREP(PWM_SIFIVE_PWMCFG_SCALE, scale);
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/*
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* The problem of output producing mixed setting as mentioned at top,
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* occurs here. To minimize the window for this problem, we are
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* calculating the register values first and then writing them
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* consecutively
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*/
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num = (u64)duty_ns * (1U << PWM_SIFIVE_CMPWIDTH);
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frac = DIV_ROUND_CLOSEST_ULL(num, period_ns);
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frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
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writel(val, priv->base + regs->cfg);
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writel(frac, priv->base + regs->cmp0 + channel *
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PWM_SIFIVE_SIZE_PWMCMP);
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return 0;
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}
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static int pwm_sifive_set_enable(struct udevice *dev, uint channel, bool enable)
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{
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struct pwm_sifive_priv *priv = dev_get_priv(dev);
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const struct pwm_sifive_regs *regs = &priv->data->regs;
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u32 val;
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debug("%s: Enable '%s'\n", __func__, dev->name);
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if (enable) {
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val = readl(priv->base + regs->cfg);
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val |= PWM_SIFIVE_PWMCFG_EN_ALWAYS;
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writel(val, priv->base + regs->cfg);
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} else {
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writel(0, priv->base + regs->cmp0 + channel *
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PWM_SIFIVE_SIZE_PWMCMP);
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}
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return 0;
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}
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static int pwm_sifive_ofdata_to_platdata(struct udevice *dev)
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{
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struct pwm_sifive_priv *priv = dev_get_priv(dev);
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priv->base = dev_read_addr_ptr(dev);
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return 0;
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}
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static int pwm_sifive_probe(struct udevice *dev)
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{
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struct pwm_sifive_priv *priv = dev_get_priv(dev);
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struct clk clk;
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int ret = 0;
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ret = clk_get_by_index(dev, 0, &clk);
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if (ret < 0) {
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debug("%s get clock fail!\n", __func__);
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return -EINVAL;
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}
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priv->freq = clk_get_rate(&clk);
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priv->data = (struct pwm_sifive_data *)dev_get_driver_data(dev);
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return 0;
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}
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static const struct pwm_ops pwm_sifive_ops = {
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.set_config = pwm_sifive_set_config,
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.set_enable = pwm_sifive_set_enable,
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};
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static const struct pwm_sifive_data pwm_data = {
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.regs = {
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.cfg = 0x00,
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.cnt = 0x08,
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.pwms = 0x10,
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.cmp0 = 0x20,
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},
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};
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static const struct udevice_id pwm_sifive_ids[] = {
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{ .compatible = "sifive,pwm0", .data = (ulong)&pwm_data},
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{ }
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};
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U_BOOT_DRIVER(pwm_sifive) = {
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.name = "pwm_sifive",
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.id = UCLASS_PWM,
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.of_match = pwm_sifive_ids,
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.ops = &pwm_sifive_ops,
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.ofdata_to_platdata = pwm_sifive_ofdata_to_platdata,
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.probe = pwm_sifive_probe,
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.priv_auto_alloc_size = sizeof(struct pwm_sifive_priv),
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};
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