Date: Wed, 26 Jul 2017 20:40:24 +0000 (UTC) From: Ian Lepore <ian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r321583 - head/sys/dev/iicbus Message-ID: <201707262040.v6QKeOJl075760@repo.freebsd.org>
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Author: ian Date: Wed Jul 26 20:40:24 2017 New Revision: 321583 URL: https://svnweb.freebsd.org/changeset/base/321583 Log: Add a pair of convenience routines for doing simple "register" read/writes on i2c devices, where the "register" can be any length. Many (perhaps most) common i2c devices are organized as a collection of (usually 1-byte-wide) registers, and are accessed by first writing a 1-byte register index/offset number, then by reading or writing the data. Generally there is an auto-increment feature so the when multiple bytes are read or written, multiple contiguous registers are accessed. Most existing slave device drivers allocate an array of iic_msg structures, fill in all the transfer info, and invoke iicbus_transfer(). These new functions commonize all that and reduce register access to a simple call with a few arguments. Modified: head/sys/dev/iicbus/iiconf.c head/sys/dev/iicbus/iiconf.h Modified: head/sys/dev/iicbus/iiconf.c ============================================================================== --- head/sys/dev/iicbus/iiconf.c Wed Jul 26 20:20:58 2017 (r321582) +++ head/sys/dev/iicbus/iiconf.c Wed Jul 26 20:40:24 2017 (r321583) @@ -470,3 +470,55 @@ iicbus_transfer_gen(device_t dev, struct iic_msg *msgs iicbus_stop(bus); return (error); } + +int +iicdev_readfrom(device_t slavedev, uint8_t regaddr, void *buffer, + uint16_t buflen, int waithow) +{ + struct iic_msg msgs[2]; + uint8_t slaveaddr; + + /* + * Two transfers back to back with a repeat-start between them; first we + * write the address-within-device, then we read from the device. + */ + slaveaddr = iicbus_get_addr(slavedev); + + msgs[0].slave = slaveaddr; + msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP; + msgs[0].len = 1; + msgs[0].buf = ®addr; + + msgs[1].slave = slaveaddr; + msgs[1].flags = IIC_M_RD; + msgs[1].len = buflen; + msgs[1].buf = buffer; + + return (iicbus_transfer_excl(slavedev, msgs, nitems(msgs), waithow)); +} + +int iicdev_writeto(device_t slavedev, uint8_t regaddr, void *buffer, + uint16_t buflen, int waithow) +{ + struct iic_msg msgs[2]; + uint8_t slaveaddr; + + /* + * Two transfers back to back with no stop or start between them; first + * we write the address then we write the data to that address, all in a + * single transfer from two scattered buffers. + */ + slaveaddr = iicbus_get_addr(slavedev); + + msgs[0].slave = slaveaddr; + msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP; + msgs[0].len = 1; + msgs[0].buf = ®addr; + + msgs[1].slave = slaveaddr; + msgs[1].flags = IIC_M_WR | IIC_M_NOSTART; + msgs[1].len = buflen; + msgs[1].buf = buffer; + + return (iicbus_transfer_excl(slavedev, msgs, nitems(msgs), waithow)); +} Modified: head/sys/dev/iicbus/iiconf.h ============================================================================== --- head/sys/dev/iicbus/iiconf.h Wed Jul 26 20:20:58 2017 (r321582) +++ head/sys/dev/iicbus/iiconf.h Wed Jul 26 20:40:24 2017 (r321583) @@ -133,6 +133,16 @@ int iicbus_transfer_excl(device_t bus, struct iic_msg int how); int iicbus_transfer_gen(device_t bus, struct iic_msg *msgs, uint32_t nmsgs); +/* + * Simple register read/write routines, but the "register" can be any size. + * The transfers are done with iicbus_transfer_excl(). Reads use a repeat-start + * between sending the address and reading; writes use a single start/stop. + */ +int iicdev_readfrom(device_t _slavedev, uint8_t _regaddr, void *_buffer, + uint16_t _buflen, int _waithow); +int iicdev_writeto(device_t _slavedev, uint8_t _regaddr, void *_buffer, + uint16_t _buflen, int _waithow); + #define IICBUS_MODVER 1 #define IICBUS_MINVER 1 #define IICBUS_MAXVER 1
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