/*      $NetBSD: uart.c,v 1.3 2022/04/11 21:23:07 andvar Exp $  */

/*
* Copyright (c) 2021 Brad Spencer <[email protected]>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#ifdef __RCSID
__RCSID("$NetBSD: uart.c,v 1.3 2022/04/11 21:23:07 andvar Exp $");
#endif

/* Functions that know how to talk to a SCMD using the uart tty
* mode or via SPI userland, which ends up being mostly the same.
*
* Some of this is the same stuff that the kernel scmd(4) driver
* ends up doing.
*/

#include <inttypes.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include <fcntl.h>
#include <string.h>
#include <limits.h>
#include <termios.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <dev/spi/spi_io.h>

#include <dev/ic/scmdreg.h>

#include "scmdctl.h"
#include "responses.h"

#define EXTERN
#include "uart.h"


static int uart_subtype = -1;
static int uart_spi_slave_addr = -1;

/* The uart tty mode of the SCMD device is useful for human or
* machine use.  However you can't really know what state it is in
* so send some junk and look for '>' character indicating a new
* command can be entered.  Usually this won't be needed, but
* you can never know when it is.
*/
int
uart_clear(int fd, bool debug)
{
       const char jcmd[4] = "qq\r\n";
       char input;
       int i;

       if (uart_subtype == UART_IS_PURE_UART) {
               i = write(fd,jcmd,4);
               if (i == 4) {
                       i = read(fd,&input,1);
                       while (input != '>') {
                               if (debug)
                                       fprintf(stderr,"uart_clear: %c\n",input);
                               i = read(fd,&input,1);
                       }
               } else {
                       return EINVAL;
               }
       }

       return 0;
}

/* The SCMD device will echo back the characters in uart tty mode.
* Eat them here.
*/
static int
pure_uart_send_cmd(int fd, const char *s, char *ibuf, int len)
{
       int i;

       i = write(fd,s,len);
       if (i == len) {
               i = read(fd,ibuf,len);
               return 0;
       } else {
               return EINVAL;
       }
}

/* In pure uart tty mode, the command is sent as text and we are
* looking for '>'.  There is not a lot that can go wrong, but
* noise on the line is one of them, and that really is not detected here.
* This is probably the least reliable method of speaking to a SCMD
* device.
*/
static int
uart_get_response(int fd, bool debug, char *obuf, int len)
{
       int n,i;
       char c;

       memset(obuf,0,len);
       n = 0;
       i = read(fd,&c,1);
       if (i == -1)
               return EINVAL;
       while (c != '>' && c != '\r' && n < len) {
               obuf[n] = c;
               if (debug)
                       fprintf(stderr,"uart_get_response: looking for EOL or NL: %d %d -%c-\n",i,n,c);
               n++;
               i = read(fd,&c,1);
       }

       if (c != '>') {
               i = read(fd,&c,1);
               if (i == -1)
                       return EINVAL;
               while (c != '>') {
                       if (debug)
                               fprintf(stderr,"uart_get_response: draining: %d -%c-\n",i,c);
                       i = read(fd,&c,1);
                       if (i == -1)
                               return EINVAL;
               }
       }

       return 0;
}

/* This handles the two uart cases.  Either pure tty uart or SPI
* userland.  The first uses text commands and the second is binary,
* but has the strange read situation that scmd(4) has.
*/
static int
uart_phy_read_register(int fd, bool debug, uint8_t reg, uint8_t *buf)
{
       int err;
       char cmdbuf[9];
       char qbuf[10];
       struct timespec ts;
       struct spi_ioctl_transfer spi_t;
       uint8_t b;

       if (SCMD_IS_HOLE(reg)) {
               *buf = SCMD_HOLE_VALUE;
               return 0;
       }

       switch (uart_subtype) {
       case UART_IS_PURE_UART:
               sprintf(cmdbuf, "R%02X\r\n", reg);
               err = pure_uart_send_cmd(fd, cmdbuf, qbuf, 5);
               if (! err) {
                       err = uart_get_response(fd, debug, qbuf, 5);
                       *buf = (uint8_t)strtol(qbuf,NULL,16);
               }
               break;
       case UART_IS_SPI_USERLAND:
               spi_t.sit_addr = uart_spi_slave_addr;
               reg = reg | 0x80;
               spi_t.sit_send = &reg;
               spi_t.sit_sendlen = 1;
               spi_t.sit_recv = NULL;
               spi_t.sit_recvlen = 0;

               err = ioctl(fd,SPI_IOCTL_TRANSFER,&spi_t);
               if (debug)
                       fprintf(stderr,"uart_phy_read_register: IOCTL UL SPI send err: %d ; reg: %02x ; xreg: %02x\n",
                           err,reg,reg & 0x7f);

               if (err == -1)
                       return errno;

               ts.tv_sec = 0;
               ts.tv_nsec = 50;
               nanosleep(&ts,NULL);

               spi_t.sit_addr = uart_spi_slave_addr;
               spi_t.sit_send = NULL;
               spi_t.sit_sendlen = 0;
               b = SCMD_HOLE_VALUE;
               spi_t.sit_recv = &b;
               spi_t.sit_recvlen = 1;

               err = ioctl(fd,SPI_IOCTL_TRANSFER,&spi_t);
               if (debug)
                       fprintf(stderr,"uart_phy_read_register: IOCTL UL SPI receive 1 err: %d ; b: %02x\n",
                           err,b);

               if (err == -1)
                       return errno;

               ts.tv_sec = 0;
               ts.tv_nsec = 50;
               nanosleep(&ts,NULL);

               *buf = (uint8_t)b;

               /* Bogus read that is needed */
               spi_t.sit_addr = uart_spi_slave_addr;
               spi_t.sit_send = NULL;
               spi_t.sit_sendlen = 0;
               b = SCMD_HOLE_VALUE;
               spi_t.sit_recv = &b;
               spi_t.sit_recvlen = 1;

               err = ioctl(fd,SPI_IOCTL_TRANSFER,&spi_t);
               if (debug)
                       fprintf(stderr,"uart_phy_read_register: IOCTL UL SPI receive 2 err: %d ; b: %02x\n",
                           err,b);

               if (err == -1)
                       return errno;

               ts.tv_sec = 0;
               ts.tv_nsec = 50;
               nanosleep(&ts,NULL);

               break;
       default:
               return EINVAL;
               break;
       }

       return err;
}

/* Like read, this handles the two uart cases. */
static int
uart_phy_write_register(int fd, bool debug, uint8_t reg, uint8_t buf)
{
       int err;
       char cmdbuf[9];
       char qbuf[10];
       struct timespec ts;
       struct spi_ioctl_transfer spi_t;

       if (SCMD_IS_HOLE(reg)) {
               return 0;
       }

       switch (uart_subtype) {
       case UART_IS_PURE_UART:
               sprintf(cmdbuf, "W%02X%02X\r\n", reg, buf);
               err = pure_uart_send_cmd(fd, cmdbuf, qbuf, 7);
               if (! err) {
                       err = uart_get_response(fd, debug, qbuf, 10);
               }
               break;
       case UART_IS_SPI_USERLAND:
               spi_t.sit_addr = uart_spi_slave_addr;
               reg = reg & 0x7f;
               spi_t.sit_send = &reg;
               spi_t.sit_sendlen = 1;
               spi_t.sit_recv = NULL;
               spi_t.sit_recvlen = 0;

               err = ioctl(fd,SPI_IOCTL_TRANSFER,&spi_t);
               if (debug)
                       fprintf(stderr,"uart_phy_write_register: IOCTL UL SPI write send 1 err: %d ; reg: %02x ; xreg: %02x\n",
                           err,reg,reg & 0x7f);

               if (err == -1)
                       return errno;

               spi_t.sit_addr = uart_spi_slave_addr;
               spi_t.sit_send = &buf;
               spi_t.sit_sendlen = 1;
               spi_t.sit_recv = NULL;
               spi_t.sit_recvlen = 0;

               err = ioctl(fd,SPI_IOCTL_TRANSFER,&spi_t);
               if (debug)
                       fprintf(stderr,"uart_phy_write_register: IOCTL UL SPI write send 2 err: %d ; buf: %02x\n",
                           err,buf);

               if (err == -1)
                       return errno;

               ts.tv_sec = 0;
               ts.tv_nsec = 50;
               nanosleep(&ts,NULL);

               break;
       default:
               return EINVAL;
               break;
       }

       return err;
}

static int
uart_local_read_register(int fd, bool debug, uint8_t reg, uint8_t reg_end, uint8_t *r)
{
       uint8_t b;
       int err = 0;

       for(int q = reg, g = 0; q <= reg_end; q++, g++) {
               err = uart_phy_read_register(fd, debug, q, &b);
               if (!err)
                       r[g] = b;
       }

       return err;
}

/* When speaking to a SCMD device in any uart mode the view port for
* chained slave modules has to be handled in userland.  This is similar
* to what the scmd(4) kernel driver ends up doing, but is much slower.
*/
static int
uart_set_view_port(int fd, bool debug, int a_module, uint8_t vpi2creg)
{
       int err;
       uint8_t vpi2caddr = (SCMD_REMOTE_ADDR_LOW + a_module) - 1;

       if (debug)
               fprintf(stderr, "uart_set_view_port: View port addr: %02x ; View port register: %02x\n",
                   vpi2caddr, vpi2creg);

       err = uart_phy_write_register(fd, debug, SCMD_REG_REM_ADDR, vpi2caddr);
       if (! err)
               err = uart_phy_write_register(fd, debug, SCMD_REG_REM_OFFSET, vpi2creg);

       return err;
}

static int
uart_remote_read_register(int fd, bool debug, int a_module, uint8_t reg, uint8_t reg_end, uint8_t *r)
{
       int err;
       int c;
       uint8_t b;

       for(int q = reg, g = 0; q <= reg_end; q++, g++) {
               err = uart_set_view_port(fd, debug, a_module, q);
               if (err)
                       break;

               b = 0xff; /* you can write anything here.. it doesn't matter */
               err = uart_phy_write_register(fd, debug, SCMD_REG_REM_READ, b);
               if (err)
                       break;

               /* So ...  there is no way to really know that the data is ready and
                * there is no way to know if there was an error in the master module reading
                * the data from the slave module.  The data sheet says wait 5ms.. so we will
                * wait a bit and see if the register cleared, but don't wait forever...  I
                * can't see how it would not be possible to read junk at times.
                */
               c = 0;
               do {
                       sleep(1);
                       err = uart_phy_read_register(fd, debug, SCMD_REG_REM_READ, &b);
                       c++;
               } while ((c < 10) && (b != 0x00) && (!err));

               /* We can only hope that whatever was read from the slave module is there */
               if (err)
                       break;
               err = uart_phy_read_register(fd, debug, SCMD_REG_REM_DATA_RD, &b);
               if (err)
                       break;
               r[g] = b;
       }

       return err;
}

void
uart_set_subtype(int subt, int spi_s_addr)
{
       uart_subtype = subt;
       uart_spi_slave_addr = spi_s_addr;

       return;
}

/* Unlike scmd(4) local reads and remote module reads are done very
* differently.
*/
int
uart_read_register(int fd, bool debug, int a_module, uint8_t reg, uint8_t reg_end, uint8_t *r)
{
       int err;

       if (reg > SCMD_LAST_REG ||
           reg_end > SCMD_LAST_REG)
               return EINVAL;

       if (reg_end < reg)
               return EINVAL;

       err = uart_clear(fd, debug);
       if (! err) {
               if (a_module == 0) {
                       err = uart_local_read_register(fd, debug, reg, reg_end, r);
               } else {
                       err = uart_remote_read_register(fd, debug, a_module, reg, reg_end, r);
               }
       }

       return err;
}

static int
uart_remote_write_register(int fd, bool debug, int a_module, uint8_t reg, uint8_t reg_v)
{
       int err;
       int c;
       uint8_t b;

       err = uart_set_view_port(fd, debug, a_module, reg);
       if (! err) {
               /* We just sort of send this write off and wait to see if the register
                * clears.  There really isn't any indication that the data made it to the
                * slave modules.
                */
               err = uart_phy_write_register(fd, debug, SCMD_REG_REM_DATA_WR, reg_v);
               if (! err) {
                       b = 0xff; /* you can write anything here.. it doesn't matter */
                       err = uart_phy_write_register(fd, debug, SCMD_REG_REM_WRITE, b);
                       if (! err) {
                               c = 0;
                               do {
                                       sleep(1);
                                       err = uart_phy_read_register(fd, debug, SCMD_REG_REM_WRITE, &b);
                                       c++;
                               } while ((c < 10) && (b != 0x00) && (!err));
                       }
               }
       }

       return err;
}

/* Like reads, writes are done very differently between scmd(4) and
* the uart modes.
*/
int
uart_write_register(int fd, bool debug, int a_module, uint8_t reg, uint8_t reg_v)
{
       int err;

       if (reg > SCMD_LAST_REG)
               return EINVAL;

       err = uart_clear(fd, debug);
       if (! err) {
               if (a_module == 0) {
                       err = uart_phy_write_register(fd, debug, reg, reg_v);
               } else {
                       err = uart_remote_write_register(fd, debug, a_module, reg, reg_v);
               }
       }

       return err;
}

/* This is a special ability to do a single SPI receive that has the
* hope of resyncing the device should it get out of sync in SPI mode.
* This will work for either SPI userland mode or scmd(4) when attached
* to the SPI bus as you can still write to /dev/spiN then too.
*/
int
uart_ul_spi_read_one(int fd, bool debug)
{
       int err = 0;
       struct timespec ts;
       struct spi_ioctl_transfer spi_t;
       uint8_t b;

       if (uart_subtype == UART_IS_SPI_USERLAND) {
               spi_t.sit_addr = uart_spi_slave_addr;
               spi_t.sit_send = NULL;
               spi_t.sit_sendlen = 0;
               b = SCMD_HOLE_VALUE;
               spi_t.sit_recv = &b;
               spi_t.sit_recvlen = 1;

               err = ioctl(fd,SPI_IOCTL_TRANSFER,&spi_t);
               if (debug)
                       fprintf(stderr,"uart_ul_spi_read_one: IOCTL UL SPI receive 1 err: %d ; b: %02x\n",
                           err,b);

               if (err == -1)
                       return errno;

               ts.tv_sec = 0;
               ts.tv_nsec = 50;
               nanosleep(&ts,NULL);
       }

       return err;
}

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