| Sylvain Munaut | 34b0d02 | 2022-09-01 18:16:19 +0200 | [diff] [blame] | 1 | /* |
| 2 | * rs422.c |
| 3 | * |
| 4 | * Copyright (C) 2022 Sylvain Munaut <tnt@246tNt.com> |
| 5 | * SPDX-License-Identifier: GPL-3.0-or-later |
| 6 | */ |
| 7 | |
| 8 | #include <stdint.h> |
| 9 | #include <stdbool.h> |
| 10 | |
| 11 | #include "console.h" |
| 12 | #include "i2c.h" |
| 13 | #include "misc.h" |
| 14 | |
| 15 | #include "config.h" |
| 16 | |
| 17 | |
| 18 | /* Local side buffer control */ |
| 19 | #define BUF_TCA9534_ADDR 0x42 |
| 20 | #define BUF_TXD_RXEN_n (1 << 0) |
| 21 | #define BUF_TXD_TXEN_n (1 << 1) |
| 22 | #define BUF_PPS_RXEN_n (1 << 4) |
| 23 | #define BUF_PPS_TXEN_n (1 << 5) |
| 24 | #define BUF_RXD_RXEN_n (1 << 6) |
| 25 | #define BUF_RXD_TXEN_n (1 << 7) |
| 26 | |
| 27 | /* Isolated side line driver control */ |
| 28 | #define LDRV_TCA9534_ADDR 0x40 |
| 29 | #define LDRV_TXD_RE_n (1 << 0) |
| 30 | #define LDRV_TXD_DE (1 << 1) |
| 31 | #define LDRV_RXD_RE_n (1 << 2) |
| 32 | #define LDRV_RXD_DE (1 << 3) |
| 33 | #define LDRV_PPS_DE (1 << 4) |
| 34 | #define LDRV_PPS_RE_n (1 << 5) |
| 35 | |
| 36 | |
| 37 | static void |
| 38 | tca9534_set_out(uint8_t dev, uint8_t data) |
| 39 | { |
| 40 | /* Check device */ |
| 41 | if (!i2c_probe(dev)) { |
| 42 | printf("[1] Unable to configure TCA9534 at address %02x\n", dev); |
| 43 | return; |
| 44 | } |
| 45 | |
| 46 | /* Output values */ |
| 47 | i2c_write_reg(dev, 1, data); |
| 48 | |
| 49 | /* No inversion */ |
| 50 | i2c_write_reg(dev, 2, 0x00); |
| 51 | |
| 52 | /* All pins as output to avoid floating pins */ |
| 53 | i2c_write_reg(dev, 3, 0x00); |
| 54 | } |
| 55 | |
| 56 | |
| 57 | void |
| 58 | rs422_init(void) |
| 59 | { |
| 60 | /* Reset GPS receiver to free I2C bus */ |
| 61 | gpio_out(3, false); |
| 62 | gpio_dir(3, true); |
| 63 | |
| 64 | /* Configure: |
| 65 | * - TXD pair: Receive |
| 66 | * - RXD pair: Transmit |
| 67 | * - PPS pair: Receive |
| 68 | */ |
| 69 | tca9534_set_out(BUF_TCA9534_ADDR, |
| 70 | BUF_TXD_TXEN_n | |
| 71 | BUF_RXD_RXEN_n | |
| 72 | BUF_PPS_TXEN_n | |
| 73 | 0 |
| 74 | ); |
| 75 | |
| 76 | tca9534_set_out(LDRV_TCA9534_ADDR, |
| 77 | LDRV_RXD_RE_n | |
| 78 | #if 0 |
| 79 | /* We don't actually TX anything to the module and |
| 80 | * this burns power ... */ |
| 81 | LDRV_RXD_DE | |
| 82 | #endif |
| 83 | 0 |
| 84 | ); |
| 85 | |
| 86 | /* Configure GPIO alt functions */ |
| 87 | /* Aux UART RX */ |
| 88 | gpio_sfn(0, true); |
| 89 | |
| 90 | /* Aux UART TX */ |
| 91 | gpio_sfn(1, true); |
| 92 | |
| 93 | /* PPS input */ |
| 94 | gpio_dir(2, false); |
| 95 | gpio_sfn(2, true); |
| 96 | } |