On Mon, 10 Mar 2014, Alexander Shiyan wrote: > Понедельник, 10 марта 2014, 7:50 -04:00 от Jon Ringle <jon@xxxxxxxxxx>: > > > > On Mon, 10 Mar 2014, Alexander Shiyan wrote: > > > > > Понедельник, 10 марта 2014, 2:26 -04:00 от jon@xxxxxxxxxx: > > > > From: Jon Ringle <jringle@xxxxxxxxxxxxx> > > > ... > > > > +config SERIAL_SC16IS7XX > > > > + tristate "SC16IS7xx RS485 serial support" > > > > + select SERIAL_CORE > > > > + default n > > > > + help > > > > + This selects support for SC16IS7xx for use as a RS485 serial port > > > > > > Documentation says: > > > The SC16IS740/750/760 is a slave I²C-bus/SPI interface to a single-channel > > > high performance UART. > > > ... > > > The SC16IS740/750/760 also provides additional advanced features such > > > as auto hardware and software flow control, automatic RS-485 support... > > > > > > So why do you position this chip as RS485 only? Automatic direction for > > > RS485 is just a feature as an addition for standart UART. > > > > You're right. This is just how we are using the chip in our board. Would a > > configuration flag in platform_data make sense to use the auto rs485 > > direction? > > You don't need a flag, just use IOCTLs. > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/drivers/tty/serial/max310x.c?id=55367c620aed6bc27a82bb1763366931d7f2ee66 > > > Any thoughts as to the latency issue I report? > > I do not understand why you chose the sccnxp driver as a template. > Use as a template max310x driver from linux-next branch. > I'm sure it will be better. I followed your advice on using max310x as a template. One thing that I'm struggling to get right is the regmap. The datasheet[1] specifies the register bits as follows: Table 33. Register address byte (I2C) Bit Name Function 7 - not used 6:3 A[3:0] UART's internal register select 2:1 CH1,0 channel select: CH1 = 0, CH0 = 0 Other values are reserved and should not be used. 0 - not used So, I need to shift the register address by 3. Here is how I have defined the regmap stuff: ------>8 [relevant code] >8------- /* SC16IS7XX register definitions */ #define SC16IS7XX_RHR_REG (0x00) /* RX FIFO */ #define SC16IS7XX_THR_REG (0x00) /* TX FIFO */ #define SC16IS7XX_IER_REG (0x01) /* Interrupt enable */ #define SC16IS7XX_IIR_REG (0x02) /* Interrupt Ident */ #define SC16IS7XX_FCR_REG (0x02) /* FIFO control */ #define SC16IS7XX_LCR_REG (0x03) /* Line Control */ #define SC16IS7XX_MCR_REG (0x04) /* Modem Control */ #define SC16IS7XX_LSR_REG (0x05) /* Line Status */ #define SC16IS7XX_MSR_REG (0x06) /* Modem Status */ #define SC16IS7XX_SPR_REG (0x07) /* Scratch Pad */ #define SC16IS7XX_TXLVL_REG (0x08) /* TX FIFO level */ #define SC16IS7XX_RXLVL_REG (0x09) /* RX FIFO level */ #define SC16IS7XX_IODIR_REG (0x0a) /* I/O Dir (750/760) */ #define SC16IS7XX_IOSTATE_REG (0x0b) /* I/O State (750/760) */ #define SC16IS7XX_IOINTENA_REG (0x0c) /* I/O Int Enable (750/760) */ #define SC16IS7XX_IOCONTROL_REG (0x0e) /* I/O Control (750/760) */ #define SC16IS7XX_EFCR_REG (0x0f) /* Extra Feature Control */ /* TX/Trigger Registers: Only if ((MCR[2] == 0) && (EFR[4] == 1)) */ #define SC16IS7XX_TCR_REG (0x06) /* Transmit control */ #define SC16IS7XX_TLR_REG (0x07) /* Trigger level */ /* Special Register set: Only if ((LCR[7] == 1) && (LCR != 0xBF)) */ #define SC16IS7XX_DLL_REG (0x00) /* Divisor Latch Low */ #define SC16IS7XX_DLH_REG (0x01) /* Divisor Latch High */ /* Enhanced Register set: Only if (LCR == 0xBF) */ #define SC16IS7XX_EFR_REG (0x02) /* Enhanced Features */ #define SC16IS7XX_XON1_REG (0x04) /* Xon1 word */ #define SC16IS7XX_XON2_REG (0x05) /* Xon2 word */ #define SC16IS7XX_XOFF1_REG (0x06) /* Xoff1 word */ #define SC16IS7XX_XOFF2_REG (0x07) /* Xoff2 word */ #define SC16IS7XX_REG_SHIFT 3 static bool sc16is7xx_reg_writeable(struct device *dev, unsigned int reg) { switch ((reg >> SC16IS7XX_REG_SHIFT) & 0xf) { case SC16IS7XX_LSR_REG: case SC16IS7XX_MSR_REG: case SC16IS7XX_TXLVL_REG: case SC16IS7XX_RXLVL_REG: return false; default: break; } return true; } static bool sc16is7xx_reg_volatile(struct device *dev, unsigned int reg) { switch ((reg >> SC16IS7XX_REG_SHIFT) & 0xf) { case SC16IS7XX_RHR_REG: case SC16IS7XX_IIR_REG: case SC16IS7XX_LSR_REG: case SC16IS7XX_MSR_REG: case SC16IS7XX_TXLVL_REG: case SC16IS7XX_RXLVL_REG: case SC16IS7XX_IOSTATE_REG: return true; default: break; } return false; } static bool sc16is7xx_reg_precious(struct device *dev, unsigned int reg) { switch ((reg >> SC16IS7XX_REG_SHIFT) & 0xf) { case SC16IS7XX_RHR_REG: case SC16IS7XX_IIR_REG: case SC16IS7XX_MSR_REG: return true; default: break; } return false; } static struct regmap_config regcfg = { .reg_bits = 8, .reg_stride = (1 << SC16IS7XX_REG_SHIFT), .val_bits = 8, .max_register = (0xf << SC16IS7XX_REG_SHIFT), .cache_type = REGCACHE_RBTREE, .writeable_reg = sc16is7xx_reg_writeable, .volatile_reg = sc16is7xx_reg_volatile, .precious_reg = sc16is7xx_reg_precious, }; ------------->8----------------- I'm not sure that I have this defined correctly. I also saw in regmap_config pad_bits, which I've tried setting to SC16IS7XX_REG_SHIFT, but when I do that, I get -EINVAL failure. Thanks, Jon [1] http://www.nxp.com/documents/data_sheet/SC16IS740_750_760.pdf
