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spf=pass smtp.mailfrom=driverdev-devel-bounces@linuxdriverproject.org smtp.helo=hemlock.osuosl.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-google-dkim=fail (message has been altered; 2048-bit rsa key) header.d=1e100.net header.i=@1e100.net header.b=rjY8k6f5; x-ptr=fail x-ptr-helo=hemlock.osuosl.org x-ptr-lookup=smtp2.osuosl.org; x-return-mx=pass smtp.domain=linuxdriverproject.org smtp.result=pass smtp_is_org_domain=yes header.domain=gmail.com header.result=pass header_is_org_domain=yes; x-tls=pass version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128 X-Remote-Delivered-To: driverdev-devel@osuosl.org X-Google-Smtp-Source: AG47ELvCf58bdmRP61K3lUZc1zKkJVpUiR6ARWAnPz5T1sG701Lyn8hnWGg/SImwY99+QQ2FAKqMgA== Date: Fri, 9 Mar 2018 20:46:40 -0300 From: Rodrigo Siqueira To: Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , Hartmut Knaack , Peter Meerwald-Stadler , Greg Kroah-Hartman , Graff Yang Subject: [PATCH 4/4] staging:iio:ad2s1210: Add comments/documentation Message-ID: <813ae9b3a8d6d9b0e6d4d4b6dda7fe354375fc8d.1520638889.git.rodrigosiqueiramelo@gmail.com> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20171215 X-BeenThere: driverdev-devel@linuxdriverproject.org X-Mailman-Version: 2.1.24 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-iio@vger.kernel.org, devel@driverdev.osuosl.org, daniel.baluta@nxp.com, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: The original code of AD2S1210 does not have documentation for structs and register configurations; this difficult the code comprehension. This patch adds structs documentation, briefly comments some register settings and acronyms, and adds little explanations of some calculation found in the code. Signed-off-by: Rodrigo Siqueira --- drivers/staging/iio/resolver/ad2s1210.c | 32 ++++++++++++++++++++++++++++++++ drivers/staging/iio/resolver/ad2s1210.h | 9 ++++++++- 2 files changed, 40 insertions(+), 1 deletion(-) diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c index ac13b99bd9cb..9bb8fd782f5a 100644 --- a/drivers/staging/iio/resolver/ad2s1210.c +++ b/drivers/staging/iio/resolver/ad2s1210.c @@ -24,8 +24,10 @@ #define DRV_NAME "ad2s1210" +/* The default value of the control register on power-up */ #define AD2S1210_DEF_CONTROL 0x7E +/* Control Register Bit */ #define AD2S1210_MSB_IS_HIGH 0x80 #define AD2S1210_MSB_IS_LOW 0x7F #define AD2S1210_PHASE_LOCK_RANGE_44 0x20 @@ -39,14 +41,23 @@ #define AD2S1210_REG_POSITION 0x80 #define AD2S1210_REG_VELOCITY 0x82 + +/* Loss of Signal (LOS) register address */ #define AD2S1210_REG_LOS_THRD 0x88 + +/* Degradation of Signal (DOS) register address */ #define AD2S1210_REG_DOS_OVR_THRD 0x89 #define AD2S1210_REG_DOS_MIS_THRD 0x8A #define AD2S1210_REG_DOS_RST_MAX_THRD 0x8B #define AD2S1210_REG_DOS_RST_MIN_THRD 0x8C + +/* Loss of Tracking (LOT) register address */ #define AD2S1210_REG_LOT_HIGH_THRD 0x8D #define AD2S1210_REG_LOT_LOW_THRD 0x8E + +/* Excitation Frequency (EXCIT) register address */ #define AD2S1210_REG_EXCIT_FREQ 0x91 + #define AD2S1210_REG_CONTROL 0x92 #define AD2S1210_REG_SOFT_RESET 0xF0 #define AD2S1210_REG_FAULT 0xFF @@ -69,6 +80,20 @@ enum ad2s1210_mode { static const unsigned int ad2s1210_resolution_value[] = { 10, 12, 14, 16 }; +/** + * struct ad2s1210_state - device instance specific state. + * @pdata: chip model specific constants, gpioin, etc + * @lock: lock to ensure state is consistent + * @sdev: the SPI device for this driver instance + * @fclkin: frequency of clock input + * @fexcit: excitation frequency + * @hysteresis: cache of whether hysteresis is enabled + * @old_data: cache of SPI communication after operation + * @resolution: chip resolution could be 10/12/14/16-bit + * @mode: indicates the operating mode + * @rx: receive buffer + * @tx: transmit buffer + */ struct ad2s1210_state { const struct ad2s1210_platform_data *pdata; struct mutex lock; @@ -82,6 +107,7 @@ struct ad2s1210_state { u8 tx[2] ____cacheline_aligned; }; +/* Maps A0 and A1 inputs to the respective mode. */ static const int ad2s1210_mode_vals[4][2] = { [MOD_POS] = { 0, 0 }, [MOD_VEL] = { 0, 1 }, @@ -137,6 +163,11 @@ int ad2s1210_update_frequency_control_word(struct ad2s1210_state *st) int ret; unsigned char fcw; + /* + * The fcw stands for frequency control word, which can be obtained + * from: + * fcw = (Excitation Frequency * 2^15) / fclkin + */ fcw = (unsigned char)(st->fexcit * (1 << 15) / st->fclkin); if (fcw < AD2S1210_MIN_FCW || fcw > AD2S1210_MAX_FCW) { dev_err(&st->sdev->dev, "ad2s1210: FCW out of range\n"); @@ -158,6 +189,7 @@ static unsigned char ad2s1210_read_resolution_pin(struct ad2s1210_state *st) return ad2s1210_resolution_value[resolution]; } +/* Maps RES0 and RES1 inputs to the respective mode. */ static const int ad2s1210_res_pins[4][2] = { { 0, 0 }, {0, 1}, {1, 0}, {1, 1} }; diff --git a/drivers/staging/iio/resolver/ad2s1210.h b/drivers/staging/iio/resolver/ad2s1210.h index e9b2147701fc..cbe21bca7638 100644 --- a/drivers/staging/iio/resolver/ad2s1210.h +++ b/drivers/staging/iio/resolver/ad2s1210.h @@ -1,5 +1,5 @@ /* - * ad2s1210.h plaform data for the ADI Resolver to Digital Converters: + * ad2s1210.h platform data for the ADI Resolver to Digital Converters: * AD2S1210 * * Copyright (c) 2010-2010 Analog Devices Inc. @@ -11,6 +11,13 @@ #ifndef _AD2S1210_H #define _AD2S1210_H +/** + * struct ad2s1210_platform_data - chip model + * @sample: sample input used to clearing the fault register + * @a: array of inputs (A0 and A1) + * @res: array of resolution inputs (RES0 and RES1) + * @gpioin: control the read operation + */ struct ad2s1210_platform_data { unsigned int sample; unsigned int a[2]; -- 2.16.2 _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel