Tom Rini | 10e4779 | 2018-05-06 17:58:06 -0400 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0+ |
Simon Glass | e6346b0 | 2015-08-03 08:19:22 -0600 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (c) 2015 Google, Inc |
| 4 | * Written by Simon Glass <sjg@chromium.org> |
Simon Glass | e6346b0 | 2015-08-03 08:19:22 -0600 | [diff] [blame] | 5 | */ |
| 6 | |
Tom Rini | abb9a04 | 2024-05-18 20:20:43 -0600 | [diff] [blame] | 7 | #include <common.h> |
Simon Glass | e6346b0 | 2015-08-03 08:19:22 -0600 | [diff] [blame] | 8 | #include <dm.h> |
| 9 | #include <errno.h> |
| 10 | #include <i2c.h> |
Simon Glass | 0f2af88 | 2020-05-10 11:40:05 -0600 | [diff] [blame] | 11 | #include <log.h> |
Simon Glass | 9bc1564 | 2020-02-03 07:36:16 -0700 | [diff] [blame] | 12 | #include <malloc.h> |
Simon Glass | 3ba929a | 2020-10-30 21:38:53 -0600 | [diff] [blame] | 13 | #include <asm/global_data.h> |
Simon Glass | e6346b0 | 2015-08-03 08:19:22 -0600 | [diff] [blame] | 14 | #include <asm/gpio.h> |
Simon Glass | dbd7954 | 2020-05-10 11:40:11 -0600 | [diff] [blame] | 15 | #include <linux/delay.h> |
Simon Glass | e6346b0 | 2015-08-03 08:19:22 -0600 | [diff] [blame] | 16 | |
| 17 | DECLARE_GLOBAL_DATA_PTR; |
| 18 | |
| 19 | struct i2c_arbitrator_priv { |
| 20 | struct gpio_desc ap_claim; |
| 21 | struct gpio_desc ec_claim; |
| 22 | uint slew_delay_us; |
| 23 | uint wait_retry_ms; |
| 24 | uint wait_free_ms; |
| 25 | }; |
| 26 | |
| 27 | int i2c_arbitrator_deselect(struct udevice *mux, struct udevice *bus, |
| 28 | uint channel) |
| 29 | { |
| 30 | struct i2c_arbitrator_priv *priv = dev_get_priv(mux); |
| 31 | int ret; |
| 32 | |
| 33 | debug("%s: %s\n", __func__, mux->name); |
| 34 | ret = dm_gpio_set_value(&priv->ap_claim, 0); |
| 35 | udelay(priv->slew_delay_us); |
| 36 | |
| 37 | return ret; |
| 38 | } |
| 39 | |
| 40 | int i2c_arbitrator_select(struct udevice *mux, struct udevice *bus, |
| 41 | uint channel) |
| 42 | { |
| 43 | struct i2c_arbitrator_priv *priv = dev_get_priv(mux); |
| 44 | unsigned start; |
| 45 | int ret; |
| 46 | |
| 47 | debug("%s: %s\n", __func__, mux->name); |
| 48 | /* Start a round of trying to claim the bus */ |
| 49 | start = get_timer(0); |
| 50 | do { |
| 51 | unsigned start_retry; |
| 52 | int waiting = 0; |
| 53 | |
| 54 | /* Indicate that we want to claim the bus */ |
| 55 | ret = dm_gpio_set_value(&priv->ap_claim, 1); |
| 56 | if (ret) |
| 57 | goto err; |
| 58 | udelay(priv->slew_delay_us); |
| 59 | |
| 60 | /* Wait for the EC to release it */ |
| 61 | start_retry = get_timer(0); |
| 62 | while (get_timer(start_retry) < priv->wait_retry_ms) { |
| 63 | ret = dm_gpio_get_value(&priv->ec_claim); |
| 64 | if (ret < 0) { |
| 65 | goto err; |
| 66 | } else if (!ret) { |
| 67 | /* We got it, so return */ |
| 68 | return 0; |
| 69 | } |
| 70 | |
| 71 | if (!waiting) |
| 72 | waiting = 1; |
| 73 | } |
| 74 | |
| 75 | /* It didn't release, so give up, wait, and try again */ |
| 76 | ret = dm_gpio_set_value(&priv->ap_claim, 0); |
| 77 | if (ret) |
| 78 | goto err; |
| 79 | |
| 80 | mdelay(priv->wait_retry_ms); |
| 81 | } while (get_timer(start) < priv->wait_free_ms); |
| 82 | |
| 83 | /* Give up, release our claim */ |
| 84 | printf("I2C: Could not claim bus, timeout %lu\n", get_timer(start)); |
| 85 | ret = -ETIMEDOUT; |
| 86 | ret = 0; |
| 87 | err: |
| 88 | return ret; |
| 89 | } |
| 90 | |
| 91 | static int i2c_arbitrator_probe(struct udevice *dev) |
| 92 | { |
| 93 | struct i2c_arbitrator_priv *priv = dev_get_priv(dev); |
| 94 | const void *blob = gd->fdt_blob; |
Simon Glass | dd79d6e | 2017-01-17 16:52:55 -0700 | [diff] [blame] | 95 | int node = dev_of_offset(dev); |
Simon Glass | e6346b0 | 2015-08-03 08:19:22 -0600 | [diff] [blame] | 96 | int ret; |
| 97 | |
| 98 | debug("%s: %s\n", __func__, dev->name); |
| 99 | priv->slew_delay_us = fdtdec_get_int(blob, node, "slew-delay-us", 0); |
| 100 | priv->wait_retry_ms = fdtdec_get_int(blob, node, "wait-retry-us", 0) / |
| 101 | 1000; |
| 102 | priv->wait_free_ms = fdtdec_get_int(blob, node, "wait-free-us", 0) / |
| 103 | 1000; |
| 104 | ret = gpio_request_by_name(dev, "our-claim-gpio", 0, &priv->ap_claim, |
| 105 | GPIOD_IS_OUT); |
| 106 | if (ret) |
| 107 | goto err; |
| 108 | ret = gpio_request_by_name(dev, "their-claim-gpios", 0, &priv->ec_claim, |
| 109 | GPIOD_IS_IN); |
| 110 | if (ret) |
| 111 | goto err_ec_gpio; |
| 112 | |
| 113 | return 0; |
| 114 | |
| 115 | err_ec_gpio: |
| 116 | dm_gpio_free(dev, &priv->ap_claim); |
| 117 | err: |
| 118 | debug("%s: ret=%d\n", __func__, ret); |
| 119 | return ret; |
| 120 | } |
| 121 | |
| 122 | static int i2c_arbitrator_remove(struct udevice *dev) |
| 123 | { |
| 124 | struct i2c_arbitrator_priv *priv = dev_get_priv(dev); |
| 125 | |
| 126 | dm_gpio_free(dev, &priv->ap_claim); |
| 127 | dm_gpio_free(dev, &priv->ec_claim); |
| 128 | |
| 129 | return 0; |
| 130 | } |
| 131 | |
| 132 | static const struct i2c_mux_ops i2c_arbitrator_ops = { |
| 133 | .select = i2c_arbitrator_select, |
| 134 | .deselect = i2c_arbitrator_deselect, |
| 135 | }; |
| 136 | |
| 137 | static const struct udevice_id i2c_arbitrator_ids[] = { |
| 138 | { .compatible = "i2c-arb-gpio-challenge" }, |
| 139 | { } |
| 140 | }; |
| 141 | |
| 142 | U_BOOT_DRIVER(i2c_arbitrator) = { |
| 143 | .name = "i2c_arbitrator", |
| 144 | .id = UCLASS_I2C_MUX, |
| 145 | .of_match = i2c_arbitrator_ids, |
| 146 | .probe = i2c_arbitrator_probe, |
| 147 | .remove = i2c_arbitrator_remove, |
| 148 | .ops = &i2c_arbitrator_ops, |
Simon Glass | 8a2b47f | 2020-12-03 16:55:17 -0700 | [diff] [blame] | 149 | .priv_auto = sizeof(struct i2c_arbitrator_priv), |
Simon Glass | e6346b0 | 2015-08-03 08:19:22 -0600 | [diff] [blame] | 150 | }; |