From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753635AbdC0OYf (ORCPT ); Mon, 27 Mar 2017 10:24:35 -0400 Received: from mail-yw0-f196.google.com ([209.85.161.196]:35925 "EHLO mail-yw0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753100AbdC0OYG (ORCPT ); Mon, 27 Mar 2017 10:24:06 -0400 Date: Mon, 27 Mar 2017 10:23:13 -0400 From: William Breathitt Gray To: Benjamin Gaignard Cc: Linux Kernel Mailing List , Jonathan Cameron , linux-iio@vger.kernel.org, Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , mwelling@ieee.org, Fabrice Gasnier , Linaro Kernel Mailman List , Benjamin Gaignard Subject: Re: [PATCH v3 1/2] iio: stm32 trigger: Add quadrature encoder device Message-ID: <20170327142313.GA11788@sophia> References: <1490607804-24889-1-git-send-email-benjamin.gaignard@st.com> <1490607804-24889-2-git-send-email-benjamin.gaignard@st.com> <20170327134727.GA13775@sophia> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 27, 2017 at 04:14:25PM +0200, Benjamin Gaignard wrote: >2017-03-27 15:47 GMT+02:00 William Breathitt Gray : >> On Mon, Mar 27, 2017 at 11:43:23AM +0200, Benjamin Gaignard wrote: >>>One of the features of STM32 trigger hardware block is a quadrature >>>encoder that can counts up/down depending of the levels and edges >>>of the selected external pins. >>> >>>This patch allow to read/write the counter, get it direction, >>>set/get quadrature modes and get scale factor. >>> >>>When counting up preset value is the limit of the counter. >>>When counting down the counter start from preset value down to 0. >>>This preset value could be set/get by using >>>/sys/bus/iio/devices/iio:deviceX/in_count0_preset attribute. >>> >>>Signed-off-by: Benjamin Gaignard >> >> Hi Benjamin, >> >> This is pretty close to the ABI I had in mind. I'm a bit confused about >> how to select some of functionality we discussed in the previous version >> so I'll write those comments inline. Overall nice work! :) >> >>> >>>version 3: >>>- fix typo in documentation >>>- change some functions names >>>--- >>> .../ABI/testing/sysfs-bus-iio-timer-stm32 | 32 +++ >>> drivers/iio/trigger/stm32-timer-trigger.c | 244 ++++++++++++++++++++- >>> include/linux/mfd/stm32-timers.h | 2 + >>> 3 files changed, 272 insertions(+), 6 deletions(-) >>> >>>diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 >>>index 6534a60..bf795ad 100644 >>>--- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 >>>+++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 >>>@@ -27,3 +27,35 @@ Description: >>> Reading returns the current sampling frequency. >>> Writing an value different of 0 set and start sampling. >>> Writing 0 stop sampling. >>>+ >>>+What: /sys/bus/iio/devices/iio:deviceX/in_count0_preset >>>+KernelVersion: 4.12 >>>+Contact: benjamin.gaignard@st.com >>>+Description: >>>+ Reading returns the current preset value. >>>+ Writing sets the preset value. >>>+ When counting up the counter starts from 0 and fires an event when reach preset value. >>>+ When counting down the counter start from preset value and fire event when reach 0. >> >> In one of the previous versions we discussed a "reset" mode of operation >> where the counter would be reset to the preset value on the rising edge >> of pin 1. How would a user select this mode of operation using this ABI >> (I assume the preset value would be the same value as in the >> in_count0_preset attribute). >> >> Also, would this "reset" mode be limited to count just the internal >> clock, or may an external pin alternatively serve as a counter source? > >In reset mode counter is clocked by the internal clock >Reset can only by drive by a rising edge of an internal signal >(represented by an IIO trigger). Ah, my apologies, I was under the incorrect impression that the reset trigger was an external signal. I think understand how it works now. > >> >>>+ >>>+What: /sys/bus/iio/devices/iio:deviceX/in_count_quadrature_mode_available >>>+KernelVersion: 4.12 >>>+Contact: benjamin.gaignard@st.com >>>+Description: >>>+ Reading returns the list possible quadrature modes. >>>+ >>>+What: /sys/bus/iio/devices/iio:deviceX/in_count0_quadrature_mode >>>+KernelVersion: 4.12 >>>+Contact: benjamin.gaignard@st.com >>>+Description: >>>+ Configure the device counter quadrature modes: >>>+ channel_A: >>>+ Encoder A input servers as the count input and B as >>>+ the UP/DOWN direction control input. >>>+ >>>+ channel_B: >>>+ Encoder B input serves as the count input and A as >>>+ the UP/DOWN direction control input. >>>+ >>>+ quadrature: >>>+ Encoder A and B inputs are mixed to get direction >>>+ and count with a scale of 0.25. >> >> If I want to select the internal clock as the counter source, how would >> I do so? Should there be an "internal_clock" mode available in the >> quadrature_mode attribute? > >To use internal clock as counter source you must select one of the modes >in in_count0_enable_mode attribute (patch 2/2) > >Counter could be drived by 3 "sources": internal clock, encoder input >and internal signal >I have in mind to keep this split in 3 attributes:enable_mode, >quadrature_mode and a futur >trigger_mode. Many thanks for the further explanation. This clears up my confusion, and I believe the interaction between these 3 attributes should work out quite well for future drivers too. William Breathitt Gray > > >> >> Sincerely, >> >> William Breathitt Gray >> >>>diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c >>>index 994b96d..7db904c 100644 >>>--- a/drivers/iio/trigger/stm32-timer-trigger.c >>>+++ b/drivers/iio/trigger/stm32-timer-trigger.c >>>@@ -15,6 +15,7 @@ >>> #include >>> >>> #define MAX_TRIGGERS 6 >>>+#define MAX_VALIDS 5 >>> >>> /* List the triggers created by each timer */ >>> static const void *triggers_table[][MAX_TRIGGERS] = { >>>@@ -32,12 +33,29 @@ >>> { TIM12_TRGO, TIM12_CH1, TIM12_CH2,}, >>> }; >>> >>>+/* List the triggers accepted by each timer */ >>>+static const void *valids_table[][MAX_VALIDS] = { >>>+ { TIM5_TRGO, TIM2_TRGO, TIM3_TRGO, TIM4_TRGO,}, >>>+ { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,}, >>>+ { TIM1_TRGO, TIM2_TRGO, TIM5_TRGO, TIM4_TRGO,}, >>>+ { TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,}, >>>+ { TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,}, >>>+ { }, /* timer 6 */ >>>+ { }, /* timer 7 */ >>>+ { TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,}, >>>+ { TIM2_TRGO, TIM3_TRGO,}, >>>+ { }, /* timer 10 */ >>>+ { }, /* timer 11 */ >>>+ { TIM4_TRGO, TIM5_TRGO,}, >>>+}; >>>+ >>> struct stm32_timer_trigger { >>> struct device *dev; >>> struct regmap *regmap; >>> struct clk *clk; >>> u32 max_arr; >>> const void *triggers; >>>+ const void *valids; >>> }; >>> >>> static int stm32_timer_start(struct stm32_timer_trigger *priv, >>>@@ -180,8 +198,7 @@ static ssize_t stm32_tt_show_master_mode(struct device *dev, >>> struct device_attribute *attr, >>> char *buf) >>> { >>>- struct iio_dev *indio_dev = dev_to_iio_dev(dev); >>>- struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ struct stm32_timer_trigger *priv = dev_get_drvdata(dev); >>> u32 cr2; >>> >>> regmap_read(priv->regmap, TIM_CR2, &cr2); >>>@@ -194,8 +211,7 @@ static ssize_t stm32_tt_store_master_mode(struct device *dev, >>> struct device_attribute *attr, >>> const char *buf, size_t len) >>> { >>>- struct iio_dev *indio_dev = dev_to_iio_dev(dev); >>>- struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ struct stm32_timer_trigger *priv = dev_get_drvdata(dev); >>> int i; >>> >>> for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) { >>>@@ -275,6 +291,216 @@ static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv) >>> return 0; >>> } >>> >>>+static int stm32_counter_read_raw(struct iio_dev *indio_dev, >>>+ struct iio_chan_spec const *chan, >>>+ int *val, int *val2, long mask) >>>+{ >>>+ struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ >>>+ switch (mask) { >>>+ case IIO_CHAN_INFO_RAW: >>>+ { >>>+ u32 cnt; >>>+ >>>+ regmap_read(priv->regmap, TIM_CNT, &cnt); >>>+ *val = cnt; >>>+ >>>+ return IIO_VAL_INT; >>>+ } >>>+ case IIO_CHAN_INFO_SCALE: >>>+ { >>>+ u32 smcr; >>>+ >>>+ regmap_read(priv->regmap, TIM_SMCR, &smcr); >>>+ smcr &= TIM_SMCR_SMS; >>>+ >>>+ *val = 1; >>>+ *val2 = 0; >>>+ >>>+ /* in quadrature case scale = 0.25 */ >>>+ if (smcr == 3) >>>+ *val2 = 2; >>>+ >>>+ return IIO_VAL_FRACTIONAL_LOG2; >>>+ } >>>+ } >>>+ >>>+ return -EINVAL; >>>+} >>>+ >>>+static int stm32_counter_write_raw(struct iio_dev *indio_dev, >>>+ struct iio_chan_spec const *chan, >>>+ int val, int val2, long mask) >>>+{ >>>+ struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ >>>+ switch (mask) { >>>+ case IIO_CHAN_INFO_RAW: >>>+ regmap_write(priv->regmap, TIM_CNT, val); >>>+ >>>+ return IIO_VAL_INT; >>>+ case IIO_CHAN_INFO_SCALE: >>>+ /* fixed scale */ >>>+ return -EINVAL; >>>+ } >>>+ >>>+ return -EINVAL; >>>+} >>>+ >>>+static const struct iio_info stm32_trigger_info = { >>>+ .driver_module = THIS_MODULE, >>>+ .read_raw = stm32_counter_read_raw, >>>+ .write_raw = stm32_counter_write_raw >>>+}; >>>+ >>>+static const char *const stm32_quadrature_modes[] = { >>>+ "channel_A", >>>+ "channel_B", >>>+ "quadrature", >>>+}; >>>+ >>>+static int stm32_set_quadrature_mode(struct iio_dev *indio_dev, >>>+ const struct iio_chan_spec *chan, >>>+ unsigned int mode) >>>+{ >>>+ struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ >>>+ regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_SMS, mode + 1); >>>+ >>>+ return 0; >>>+} >>>+ >>>+static int stm32_get_quadrature_mode(struct iio_dev *indio_dev, >>>+ const struct iio_chan_spec *chan) >>>+{ >>>+ struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ u32 smcr; >>>+ >>>+ regmap_read(priv->regmap, TIM_SMCR, &smcr); >>>+ smcr &= TIM_SMCR_SMS; >>>+ >>>+ return smcr - 1; >>>+} >>>+ >>>+static const struct iio_enum stm32_quadrature_mode_enum = { >>>+ .items = stm32_quadrature_modes, >>>+ .num_items = ARRAY_SIZE(stm32_quadrature_modes), >>>+ .set = stm32_set_quadrature_mode, >>>+ .get = stm32_get_quadrature_mode >>>+}; >>>+ >>>+static const char *const stm32_count_direction_states[] = { >>>+ "up", >>>+ "down" >>>+}; >>>+ >>>+static int stm32_set_count_direction(struct iio_dev *indio_dev, >>>+ const struct iio_chan_spec *chan, >>>+ unsigned int mode) >>>+{ >>>+ struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ >>>+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_DIR, mode); >>>+ >>>+ return 0; >>>+} >>>+ >>>+static int stm32_get_count_direction(struct iio_dev *indio_dev, >>>+ const struct iio_chan_spec *chan) >>>+{ >>>+ struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ u32 cr1; >>>+ >>>+ regmap_read(priv->regmap, TIM_CR1, &cr1); >>>+ >>>+ return (cr1 & TIM_CR1_DIR); >>>+} >>>+ >>>+static const struct iio_enum stm32_count_direction_enum = { >>>+ .items = stm32_count_direction_states, >>>+ .num_items = ARRAY_SIZE(stm32_count_direction_states), >>>+ .set = stm32_set_count_direction, >>>+ .get = stm32_get_count_direction >>>+}; >>>+ >>>+static ssize_t stm32_count_get_preset(struct iio_dev *indio_dev, >>>+ uintptr_t private, >>>+ const struct iio_chan_spec *chan, >>>+ char *buf) >>>+{ >>>+ struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ u32 arr; >>>+ >>>+ regmap_read(priv->regmap, TIM_ARR, &arr); >>>+ >>>+ return snprintf(buf, PAGE_SIZE, "%u\n", arr); >>>+} >>>+ >>>+static ssize_t stm32_count_set_preset(struct iio_dev *indio_dev, >>>+ uintptr_t private, >>>+ const struct iio_chan_spec *chan, >>>+ const char *buf, size_t len) >>>+{ >>>+ struct stm32_timer_trigger *priv = iio_priv(indio_dev); >>>+ unsigned int preset; >>>+ int ret; >>>+ >>>+ ret = kstrtouint(buf, 0, &preset); >>>+ if (ret) >>>+ return ret; >>>+ >>>+ regmap_write(priv->regmap, TIM_ARR, preset); >>>+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE); >>>+ >>>+ return len; >>>+} >>>+ >>>+static const struct iio_chan_spec_ext_info stm32_trigger_count_info[] = { >>>+ { >>>+ .name = "preset", >>>+ .shared = IIO_SEPARATE, >>>+ .read = stm32_count_get_preset, >>>+ .write = stm32_count_set_preset >>>+ }, >>>+ IIO_ENUM("count_direction", IIO_SEPARATE, &stm32_count_direction_enum), >>>+ IIO_ENUM_AVAILABLE("count_direction", &stm32_count_direction_enum), >>>+ IIO_ENUM("quadrature_mode", IIO_SEPARATE, &stm32_quadrature_mode_enum), >>>+ IIO_ENUM_AVAILABLE("quadrature_mode", &stm32_quadrature_mode_enum), >>>+ {} >>>+}; >>>+ >>>+static const struct iio_chan_spec stm32_trigger_channel = { >>>+ .type = IIO_COUNT, >>>+ .channel = 0, >>>+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), >>>+ .ext_info = stm32_trigger_count_info, >>>+ .indexed = 1 >>>+}; >>>+ >>>+static struct stm32_timer_trigger *stm32_setup_counter_device(struct device *dev) >>>+{ >>>+ struct iio_dev *indio_dev; >>>+ int ret; >>>+ >>>+ indio_dev = devm_iio_device_alloc(dev, >>>+ sizeof(struct stm32_timer_trigger)); >>>+ if (!indio_dev) >>>+ return NULL; >>>+ >>>+ indio_dev->name = dev_name(dev); >>>+ indio_dev->dev.parent = dev; >>>+ indio_dev->info = &stm32_trigger_info; >>>+ indio_dev->num_channels = 1; >>>+ indio_dev->channels = &stm32_trigger_channel; >>>+ indio_dev->dev.of_node = dev->of_node; >>>+ >>>+ ret = devm_iio_device_register(dev, indio_dev); >>>+ if (ret) >>>+ return NULL; >>>+ >>>+ return iio_priv(indio_dev); >>>+} >>>+ >>> /** >>> * is_stm32_timer_trigger >>> * @trig: trigger to be checked >>>@@ -299,10 +525,15 @@ static int stm32_timer_trigger_probe(struct platform_device *pdev) >>> if (of_property_read_u32(dev->of_node, "reg", &index)) >>> return -EINVAL; >>> >>>- if (index >= ARRAY_SIZE(triggers_table)) >>>+ if (index >= ARRAY_SIZE(triggers_table) || >>>+ index >= ARRAY_SIZE(valids_table)) >>> return -EINVAL; >>> >>>- priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); >>>+ /* Create an IIO device only if we have triggers to be validated */ >>>+ if (*valids_table[index]) >>>+ priv = stm32_setup_counter_device(dev); >>>+ else >>>+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); >>> >>> if (!priv) >>> return -ENOMEM; >>>@@ -312,6 +543,7 @@ static int stm32_timer_trigger_probe(struct platform_device *pdev) >>> priv->clk = ddata->clk; >>> priv->max_arr = ddata->max_arr; >>> priv->triggers = triggers_table[index]; >>>+ priv->valids = valids_table[index]; >>> >>> ret = stm32_setup_iio_triggers(priv); >>> if (ret) >>>diff --git a/include/linux/mfd/stm32-timers.h b/include/linux/mfd/stm32-timers.h >>>index d030004..4a0abbc 100644 >>>--- a/include/linux/mfd/stm32-timers.h >>>+++ b/include/linux/mfd/stm32-timers.h >>>@@ -21,6 +21,7 @@ >>> #define TIM_CCMR1 0x18 /* Capt/Comp 1 Mode Reg */ >>> #define TIM_CCMR2 0x1C /* Capt/Comp 2 Mode Reg */ >>> #define TIM_CCER 0x20 /* Capt/Comp Enable Reg */ >>>+#define TIM_CNT 0x24 /* Counter */ >>> #define TIM_PSC 0x28 /* Prescaler */ >>> #define TIM_ARR 0x2c /* Auto-Reload Register */ >>> #define TIM_CCR1 0x34 /* Capt/Comp Register 1 */ >>>@@ -30,6 +31,7 @@ >>> #define TIM_BDTR 0x44 /* Break and Dead-Time Reg */ >>> >>> #define TIM_CR1_CEN BIT(0) /* Counter Enable */ >>>+#define TIM_CR1_DIR BIT(4) /* Counter Direction */ >>> #define TIM_CR1_ARPE BIT(7) /* Auto-reload Preload Ena */ >>> #define TIM_CR2_MMS (BIT(4) | BIT(5) | BIT(6)) /* Master mode selection */ >>> #define TIM_SMCR_SMS (BIT(0) | BIT(1) | BIT(2)) /* Slave mode selection */ >>>-- >>>1.9.1 >>> > > > >-- >Benjamin Gaignard > >Graphic Study Group > >Linaro.org │ Open source software for ARM SoCs > >Follow Linaro: Facebook | Twitter | Blog