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Volkmer" To: rafael.v.volkmer@gmail.com Cc: linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, ukleinek@kernel.org Subject: [PATCH v3 2/3] pwm: ehrpwm: add get_state function to retrieve PWM channel state Date: Fri, 7 Feb 2025 18:32:34 -0300 Message-Id: <20250207213234.1026-1-rafael.v.volkmer@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20250207212954.934-1-rafael.v.volkmer@gmail.com> References: <20250207212954.934-1-rafael.v.volkmer@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The ehrpwm driver was missing a get_state function, which is required to properly retrieve the current state of the PWM channel. This commit adds the ehrpwm_get_state() function, allowing users to query the enabled state, period, duty cycle, and polarity of the PWM output. The function reads the relevant registers (AQCSFRC, AQCTLx, TBPRD, CMPA) to determine: - Whether the PWM is enabled or disabled - The configured period and duty cycle - The polarity based on action-qualifier configurations Additionally, this commit updates the pwm_ops structure to include .get_state, ensuring proper integration with the PWM subsystem. Signed-off-by: Rafael V. Volkmer --- drivers/pwm/pwm-tiehrpwm.c | 122 +++++++++++++++++++++++++++++++++++++ 1 file changed, 122 insertions(+) diff --git a/drivers/pwm/pwm-tiehrpwm.c b/drivers/pwm/pwm-tiehrpwm.c index 50516f46ab04..52527136c507 100644 --- a/drivers/pwm/pwm-tiehrpwm.c +++ b/drivers/pwm/pwm-tiehrpwm.c @@ -81,7 +81,9 @@ #define AQCTL_ZRO_MASK GENMASK(1, 0) #define AQCTL_PRD_MASK GENMASK(3, 2) #define AQCTL_CAU_MASK GENMASK(5, 4) +#define AQCTL_CAD_MASK GENMASK(7, 6) #define AQCTL_CBU_MASK GENMASK(9, 8) +#define AQCTL_CBD_MASK GENMASK(11, 10) /* * FORCE LOW => 0b01 @@ -495,9 +497,129 @@ static int ehrpwm_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, return err; } +/** + * ehrpwm_get_state - Retrieves the current state of the eHRPWM channel + * @chip: pointer to the PWM chip structure + * @pwm: pointer to the PWM device structure + * @state: pointer to the pwm_state structure to be filled + * + * @return: 0 on success or a negative error code on failure + */ +static int ehrpwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + int ret = 0u; + + struct ehrpwm_pwm_chip *pc = NULL; + + unsigned long long tbclk_rate = 0u; + + /* Registers */ + u16 aqcsfrc_reg = 0u; + u16 aqctl_reg = 0u; + u16 tbprd_reg = 0u; + u16 cmpa_reg = 0u; + + /* Bits */ + u8 csf_bits = 0u; + + /* Values */ + u64 period_cycles = 0u; + u64 duty_cycles = 0u; + + /* Actions */ + u8 up_action = 0u; + u8 down_action = 0u; + + if (chip == NULL || pwm == NULL || state == NULL) + return -EINVAL; + + pc = to_ehrpwm_pwm_chip(chip); + if (pc == NULL || pwm == NULL || state == NULL) + return -EINVAL; + + tbclk_rate = clk_get_rate(pc->tbclk); + if (tbclk_rate <= 0) + return -EINVAL; + + /*< Get if EHRPWM is enable by checking registers values >*/ + + /* + * The 'hwpwm' field identifies which hardware output channel (e.g., + * 0 for channel A and 1 for channel B) of the eHRPWM module is in use. + */ + if (pwm->hwpwm == 0) { + aqcsfrc_reg = readw(pc->mmio_base + AQCSFRC); + csf_bits = FIELD_GET(AQCSFRC_CSFA_MASK, aqcsfrc_reg); + aqctl_reg = readw(pc->mmio_base + AQCTLA); + } else { + aqcsfrc_reg = readw(pc->mmio_base + AQCSFRC); + csf_bits = FIELD_GET(AQCSFRC_CSFB_MASK, aqcsfrc_reg); + aqctl_reg = readw(pc->mmio_base + AQCTLB); + } + + if (csf_bits) + state->enabled = false; + + else if (aqctl_reg) + state->enabled = true; + + /*< Get EHRPWM Period by checking registers values >*/ + tbprd_reg = readw(pc->mmio_base + TBPRD); + period_cycles = (u64)(tbprd_reg + 1u); + + /* + * period (in ns) = (period_cycles * 1e9) / tbclk_rate + * Using DIV_ROUND_UP_ULL to avoid floating-point operations. + */ + state->period = DIV_ROUND_UP_ULL(period_cycles * NSEC_PER_SEC, tbclk_rate); + + /*< Get EHRPWM Duty Cycle by checking registers values >*/ + cmpa_reg = readw(pc->mmio_base + CMPA); + duty_cycles = cmpa_reg; + + /* + * duty_cycle (in ns) = (duty_cycles * 1e9) / tbclk_rate + * Using DIV_ROUND_UP_ULL to avoid floating-point operations. + */ + state->duty_cycle = DIV_ROUND_UP_ULL(duty_cycles * NSEC_PER_SEC, tbclk_rate); + + /*< Get EHRPWM polarity by checking registers values >*/ + + /* + * The 'hwpwm' field identifies which hardware output channel (e.g., + * 0 for channel A and 1 for channel B) of the eHRPWM module is in use. + */ + if (pwm->hwpwm == 0) { + aqctl_reg = readw(pc->mmio_base + AQCTLA); + up_action = FIELD_GET(AQCTL_CAU_MASK, aqctl_reg); + down_action = FIELD_GET(AQCTL_CAD_MASK, aqctl_reg); + } else { + aqctl_reg = readw(pc->mmio_base + AQCTLB); + up_action = FIELD_GET(AQCTL_CBU_MASK, aqctl_reg); + down_action = FIELD_GET(AQCTL_CBD_MASK, aqctl_reg); + } + + /* + * Evaluate the actions to determine the PWM polarity: + * - If an up-count event sets the output (AQCTL_FRCHIGH) and a down-count + * event clears it (AQ_CLEAR), then polarity is NORMAL. + * - If an up-count event clears the output (AQ_CLEAR) and a down-count + * event sets it (AQCTL_FRCLOW), then polarity is INVERSED. + */ + if (up_action == AQCTL_FRCHIGH && down_action == AQCTL_FRCLOW) + state->polarity = PWM_POLARITY_NORMAL; + + else if (up_action == AQCTL_FRCLOW && down_action == AQCTL_FRCHIGH) + state->polarity = PWM_POLARITY_INVERSED; + + return ret; +} + static const struct pwm_ops ehrpwm_pwm_ops = { .free = ehrpwm_pwm_free, .apply = ehrpwm_pwm_apply, + .get_state = ehrpwm_get_state, }; static const struct of_device_id ehrpwm_of_match[] = { -- 2.25.1