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([2a01:e0a:982:cbb0:4595:23ef:4ba2:2d19]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42f89ed957asm99662485e9.44.2024.10.08.00.30.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Oct 2024 00:30:34 -0700 (PDT) Message-ID: <478259f2-b7ec-4664-95cb-3ab56ae6d529@linaro.org> Date: Tue, 8 Oct 2024 09:30:33 +0200 Precedence: bulk X-Mailing-List: linux-pwm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: neil.armstrong@linaro.org Reply-To: neil.armstrong@linaro.org Subject: Re: [PATCH 1/3] pwm: meson: Support constant and polarity bits To: George Stark , u.kleine-koenig@pengutronix.de, khilman@baylibre.com, jbrunet@baylibre.com, martin.blumenstingl@googlemail.com Cc: linux-pwm@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel@salutedevices.com References: <20241007193203.1753326-1-gnstark@salutedevices.com> <20241007193203.1753326-2-gnstark@salutedevices.com> Content-Language: en-US, fr Autocrypt: addr=neil.armstrong@linaro.org; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKk5laWwgQXJtc3Ryb25nIDxuZWlsLmFybXN0cm9uZ0BsaW5hcm8ub3JnPsLAkQQTAQoA OwIbIwULCQgHAwUVCgkICwUWAgMBAAIeAQIXgBYhBInsPQWERiF0UPIoSBaat7Gkz/iuBQJk Q5wSAhkBAAoJEBaat7Gkz/iuyhMIANiD94qDtUTJRfEW6GwXmtKWwl/mvqQtaTtZID2dos04 YqBbshiJbejgVJjy+HODcNUIKBB3PSLaln4ltdsV73SBcwUNdzebfKspAQunCM22Mn6FBIxQ GizsMLcP/0FX4en9NaKGfK6ZdKK6kN1GR9YffMJd2P08EO8mHowmSRe/ExAODhAs9W7XXExw UNCY4pVJyRPpEhv373vvff60bHxc1k/FF9WaPscMt7hlkbFLUs85kHtQAmr8pV5Hy9ezsSRa GzJmiVclkPc2BY592IGBXRDQ38urXeM4nfhhvqA50b/nAEXc6FzqgXqDkEIwR66/Gbp0t3+r yQzpKRyQif3OwE0ETVkGzwEIALyKDN/OGURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYp QTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXMcoJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+ SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hiSvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY 4yG6xI99NIPEVE9lNBXBKIlewIyVlkOaYvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoM Mtsyw18YoX9BqMFInxqYQQ3j/HpVgTSvmo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUX oUk33HEAEQEAAcLAXwQYAQIACQUCTVkGzwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfn M7IbRuiSZS1unlySUVYu3SD6YBYnNi3G5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa3 3eDIHu/zr1HMKErm+2SD6PO9umRef8V82o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCS KmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy 4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJC3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTT QbM0WUIBIcGmq38+OgUsMYu4NzLu7uZFAcmp6h8g Organization: Linaro In-Reply-To: <20241007193203.1753326-2-gnstark@salutedevices.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 07/10/2024 21:32, George Stark wrote: > Newer meson PWM IPs support constant and polarity bits. Support them to > correctly implement constant and inverted output levels. > > Using constant bit allows to have truly stable low or high output level. > Since hi and low regs internally increment its values by 1 just writing > zero to any of them gives 1 clock count impulse. If constant bit is set > zero value in hi and low regs is not incremented. > > Using polarity bit instead of swapping hi and low reg values allows to > correctly identify inversion in .get_state(). > > Signed-off-by: George Stark > --- > drivers/pwm/pwm-meson.c | 75 +++++++++++++++++++++++++++++++++++++---- > 1 file changed, 69 insertions(+), 6 deletions(-) > > diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c > index 98e6c1533312..5d51404bdce3 100644 > --- a/drivers/pwm/pwm-meson.c > +++ b/drivers/pwm/pwm-meson.c > @@ -6,7 +6,7 @@ > * PWM output is achieved by calculating a clock that permits calculating > * two periods (low and high). The counter then has to be set to switch after > * N cycles for the first half period. > - * The hardware has no "polarity" setting. This driver reverses the period > + * Partly the hardware has no "polarity" setting. This driver reverses the period > * cycles (the low length is inverted with the high length) for > * PWM_POLARITY_INVERSED. This means that .get_state cannot read the polarity > * from the hardware. > @@ -56,6 +56,10 @@ > #define MISC_B_CLK_SEL_SHIFT 6 > #define MISC_A_CLK_SEL_SHIFT 4 > #define MISC_CLK_SEL_MASK 0x3 > +#define MISC_B_CONSTANT_EN BIT(29) > +#define MISC_A_CONSTANT_EN BIT(28) > +#define MISC_B_INVERT_EN BIT(27) > +#define MISC_A_INVERT_EN BIT(26) > #define MISC_B_EN BIT(1) > #define MISC_A_EN BIT(0) Nice, seems I completely missed those 2 features! > > @@ -68,6 +72,8 @@ static struct meson_pwm_channel_data { > u8 clk_div_shift; > u8 clk_en_shift; > u32 pwm_en_mask; > + u32 const_en_mask; > + u32 inv_en_mask; > } meson_pwm_per_channel_data[MESON_NUM_PWMS] = { > { > .reg_offset = REG_PWM_A, > @@ -75,6 +81,8 @@ static struct meson_pwm_channel_data { > .clk_div_shift = MISC_A_CLK_DIV_SHIFT, > .clk_en_shift = MISC_A_CLK_EN_SHIFT, > .pwm_en_mask = MISC_A_EN, > + .const_en_mask = MISC_A_CONSTANT_EN, > + .inv_en_mask = MISC_A_INVERT_EN, > }, > { > .reg_offset = REG_PWM_B, > @@ -82,6 +90,8 @@ static struct meson_pwm_channel_data { > .clk_div_shift = MISC_B_CLK_DIV_SHIFT, > .clk_en_shift = MISC_B_CLK_EN_SHIFT, > .pwm_en_mask = MISC_B_EN, > + .const_en_mask = MISC_B_CONSTANT_EN, > + .inv_en_mask = MISC_B_INVERT_EN, > } > }; > > @@ -99,6 +109,8 @@ struct meson_pwm_channel { > struct meson_pwm_data { > const char *const parent_names[MESON_NUM_MUX_PARENTS]; > int (*channels_init)(struct pwm_chip *chip); > + bool has_constant; > + bool has_polarity; > }; > > struct meson_pwm { > @@ -160,7 +172,7 @@ static int meson_pwm_calc(struct pwm_chip *chip, struct pwm_device *pwm, > * Fixing this needs some care however as some machines might rely on > * this. > */ > - if (state->polarity == PWM_POLARITY_INVERSED) > + if (state->polarity == PWM_POLARITY_INVERSED && !meson->data->has_polarity) > duty = period - duty; > > freq = div64_u64(NSEC_PER_SEC * 0xffffULL, period); > @@ -204,6 +216,46 @@ static int meson_pwm_calc(struct pwm_chip *chip, struct pwm_device *pwm, > return 0; > } > > +static void meson_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, > + bool inverted) > +{ > + struct meson_pwm *meson = to_meson_pwm(chip); > + const struct meson_pwm_channel_data *channel_data; > + unsigned long flags; > + u32 value; > + > + channel_data = &meson_pwm_per_channel_data[pwm->hwpwm]; > + > + spin_lock_irqsave(&meson->lock, flags); > + value = readl(meson->base + REG_MISC_AB); > + if (inverted) > + value |= channel_data->inv_en_mask; > + else > + value &= ~channel_data->inv_en_mask; > + writel(value, meson->base + REG_MISC_AB); > + spin_unlock_irqrestore(&meson->lock, flags); > +} > + > +static void meson_pwm_set_constant(struct pwm_chip *chip, struct pwm_device *pwm, > + bool enable) > +{ > + struct meson_pwm *meson = to_meson_pwm(chip); > + const struct meson_pwm_channel_data *channel_data; > + unsigned long flags; > + u32 value; > + > + channel_data = &meson_pwm_per_channel_data[pwm->hwpwm]; > + > + spin_lock_irqsave(&meson->lock, flags); > + value = readl(meson->base + REG_MISC_AB); > + if (enable) > + value |= channel_data->const_en_mask; > + else > + value &= ~channel_data->const_en_mask; > + writel(value, meson->base + REG_MISC_AB); > + spin_unlock_irqrestore(&meson->lock, flags); > +} Those functions looks quite complicated, why can't they be part of meson_pwm_enable/disable where we already write REG_MISC_AB ? > + > static void meson_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) > { > struct meson_pwm *meson = to_meson_pwm(chip); > @@ -255,9 +307,9 @@ static int meson_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > int err = 0; > > if (!state->enabled) { > - if (state->polarity == PWM_POLARITY_INVERSED) { > + if (state->polarity == PWM_POLARITY_INVERSED && !meson->data->has_polarity) { > /* > - * This IP block revision doesn't have an "always high" > + * Some of IP block revisions don't have an "always high" > * setting which we can use for "inverted disabled". > * Instead we achieve this by setting mux parent with > * highest rate and minimum divider value, resulting > @@ -284,6 +336,14 @@ static int meson_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > meson_pwm_enable(chip, pwm); > } > > + if (meson->data->has_constant) > + meson_pwm_set_constant(chip, pwm, > + state->duty_cycle == state->period || > + !state->duty_cycle); > + if (meson->data->has_polarity) > + meson_pwm_set_polarity(chip, pwm, > + !(state->polarity == PWM_POLARITY_NORMAL)); > + > return 0; > } > > @@ -318,6 +378,11 @@ static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > value = readl(meson->base + REG_MISC_AB); > state->enabled = value & channel_data->pwm_en_mask; > > + if (meson->data->has_polarity && (value & channel_data->inv_en_mask)) > + state->polarity = PWM_POLARITY_INVERSED; > + else > + state->polarity = PWM_POLARITY_NORMAL; > + > value = readl(meson->base + channel_data->reg_offset); > channel->lo = FIELD_GET(PWM_LOW_MASK, value); > channel->hi = FIELD_GET(PWM_HIGH_MASK, value); > @@ -325,8 +390,6 @@ static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->lo + channel->hi); > state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm, channel->hi); > > - state->polarity = PWM_POLARITY_NORMAL; > - > return 0; > } > > -- > 2.25.1 >