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https://github.com/AsahiLinux/u-boot
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dfb8470fd0
At present the counter never hits the comparitor in this case. Add a
special case.
This ensures that the snow backlight works when at full brightness.
Fixes: 76c2ff3e5f video: backlight: fix pwm's duty cycle calculation
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
122 lines
2.8 KiB
C
122 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright 2016 Google Inc.
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*/
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#include <common.h>
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#include <dm.h>
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#include <log.h>
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#include <pwm.h>
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#include <asm/io.h>
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#include <asm/arch/clk.h>
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#include <asm/arch/clock.h>
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#include <asm/arch/pwm.h>
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struct exynos_pwm_priv {
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struct s5p_timer *regs;
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};
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static int exynos_pwm_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 exynos_pwm_priv *priv = dev_get_priv(dev);
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struct s5p_timer *regs = priv->regs;
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unsigned int offset, prescaler;
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uint div = 4, rate, rate_ns;
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u32 val;
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u32 tcnt, tcmp, tcon;
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if (channel >= 5)
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return -EINVAL;
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debug("%s: Configure '%s' channel %u, period_ns %u, duty_ns %u\n",
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__func__, dev->name, channel, period_ns, duty_ns);
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val = readl(®s->tcfg0);
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prescaler = (channel < 2 ? val : (val >> 8)) & 0xff;
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div = (readl(®s->tcfg1) >> MUX_DIV_SHIFT(channel)) & 0xf;
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rate = get_pwm_clk() / ((prescaler + 1) * (1 << div));
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debug("%s: pwm_clk %lu, rate %u\n", __func__, get_pwm_clk(), rate);
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if (channel < 4) {
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rate_ns = 1000000000 / rate;
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tcnt = period_ns / rate_ns;
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tcmp = duty_ns / rate_ns;
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debug("%s: tcnt %u, tcmp %u\n", __func__, tcnt, tcmp);
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/* Ensure that the comparitor will actually hit the target */
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if (tcmp == tcnt)
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tcmp = tcnt - 1;
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offset = channel * 3;
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writel(tcnt, ®s->tcntb0 + offset);
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writel(tcmp, ®s->tcmpb0 + offset);
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}
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tcon = readl(®s->tcon);
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tcon |= TCON_UPDATE(channel);
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if (channel < 4)
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tcon |= TCON_AUTO_RELOAD(channel);
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else
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tcon |= TCON4_AUTO_RELOAD;
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writel(tcon, ®s->tcon);
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tcon &= ~TCON_UPDATE(channel);
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writel(tcon, ®s->tcon);
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return 0;
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}
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static int exynos_pwm_set_enable(struct udevice *dev, uint channel,
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bool enable)
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{
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struct exynos_pwm_priv *priv = dev_get_priv(dev);
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struct s5p_timer *regs = priv->regs;
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u32 mask;
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if (channel >= 4)
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return -EINVAL;
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debug("%s: Enable '%s' channel %u\n", __func__, dev->name, channel);
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mask = TCON_START(channel);
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clrsetbits_le32(®s->tcon, mask, enable ? mask : 0);
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return 0;
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}
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static int exynos_pwm_probe(struct udevice *dev)
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{
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struct exynos_pwm_priv *priv = dev_get_priv(dev);
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struct s5p_timer *regs = priv->regs;
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writel(PRESCALER_0 | PRESCALER_1 << 8, ®s->tcfg0);
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return 0;
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}
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static int exynos_pwm_of_to_plat(struct udevice *dev)
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{
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struct exynos_pwm_priv *priv = dev_get_priv(dev);
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priv->regs = dev_read_addr_ptr(dev);
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return 0;
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}
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static const struct pwm_ops exynos_pwm_ops = {
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.set_config = exynos_pwm_set_config,
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.set_enable = exynos_pwm_set_enable,
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};
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static const struct udevice_id exynos_channels[] = {
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{ .compatible = "samsung,exynos4210-pwm" },
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{ }
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};
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U_BOOT_DRIVER(exynos_pwm) = {
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.name = "exynos_pwm",
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.id = UCLASS_PWM,
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.of_match = exynos_channels,
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.ops = &exynos_pwm_ops,
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.probe = exynos_pwm_probe,
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.of_to_plat = exynos_pwm_of_to_plat,
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.priv_auto = sizeof(struct exynos_pwm_priv),
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};
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