Thomas Gleixner | c942fdd | 2019-05-27 08:55:06 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 2 | /* |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 3 | * SPI host driver for ICP DAS LP-8841 RTC |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 4 | * |
| 5 | * Copyright (C) 2016 Sergei Ianovich |
| 6 | * |
| 7 | * based on |
| 8 | * |
| 9 | * Dallas DS1302 RTC Support |
| 10 | * Copyright (C) 2002 David McCullough |
| 11 | * Copyright (C) 2003 - 2007 Paul Mundt |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 12 | */ |
| 13 | #include <linux/delay.h> |
| 14 | #include <linux/kernel.h> |
| 15 | #include <linux/module.h> |
| 16 | #include <linux/platform_device.h> |
| 17 | #include <linux/of.h> |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 18 | #include <linux/spi/spi.h> |
| 19 | |
| 20 | #define DRIVER_NAME "spi_lp8841_rtc" |
| 21 | |
| 22 | #define SPI_LP8841_RTC_CE 0x01 |
| 23 | #define SPI_LP8841_RTC_CLK 0x02 |
| 24 | #define SPI_LP8841_RTC_nWE 0x04 |
| 25 | #define SPI_LP8841_RTC_MOSI 0x08 |
| 26 | #define SPI_LP8841_RTC_MISO 0x01 |
| 27 | |
| 28 | /* |
| 29 | * REVISIT If there is support for SPI_3WIRE and SPI_LSB_FIRST in SPI |
| 30 | * GPIO driver, this SPI driver can be replaced by a simple GPIO driver |
| 31 | * providing 3 GPIO pins. |
| 32 | */ |
| 33 | |
| 34 | struct spi_lp8841_rtc { |
| 35 | void *iomem; |
| 36 | unsigned long state; |
| 37 | }; |
| 38 | |
| 39 | static inline void |
| 40 | setsck(struct spi_lp8841_rtc *data, int is_on) |
| 41 | { |
| 42 | if (is_on) |
| 43 | data->state |= SPI_LP8841_RTC_CLK; |
| 44 | else |
| 45 | data->state &= ~SPI_LP8841_RTC_CLK; |
| 46 | writeb(data->state, data->iomem); |
| 47 | } |
| 48 | |
| 49 | static inline void |
| 50 | setmosi(struct spi_lp8841_rtc *data, int is_on) |
| 51 | { |
| 52 | if (is_on) |
| 53 | data->state |= SPI_LP8841_RTC_MOSI; |
| 54 | else |
| 55 | data->state &= ~SPI_LP8841_RTC_MOSI; |
| 56 | writeb(data->state, data->iomem); |
| 57 | } |
| 58 | |
| 59 | static inline int |
| 60 | getmiso(struct spi_lp8841_rtc *data) |
| 61 | { |
| 62 | return ioread8(data->iomem) & SPI_LP8841_RTC_MISO; |
| 63 | } |
| 64 | |
| 65 | static inline u32 |
| 66 | bitbang_txrx_be_cpha0_lsb(struct spi_lp8841_rtc *data, |
| 67 | unsigned usecs, unsigned cpol, unsigned flags, |
| 68 | u32 word, u8 bits) |
| 69 | { |
| 70 | /* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */ |
| 71 | |
| 72 | u32 shift = 32 - bits; |
| 73 | /* clock starts at inactive polarity */ |
| 74 | for (; likely(bits); bits--) { |
| 75 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 76 | /* setup LSB (to target) on leading edge */ |
Andy Shevchenko | c397f09 | 2023-07-10 18:49:28 +0300 | [diff] [blame] | 77 | if ((flags & SPI_CONTROLLER_NO_TX) == 0) |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 78 | setmosi(data, (word & 1)); |
| 79 | |
| 80 | usleep_range(usecs, usecs + 1); /* T(setup) */ |
| 81 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 82 | /* sample LSB (from target) on trailing edge */ |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 83 | word >>= 1; |
Andy Shevchenko | c397f09 | 2023-07-10 18:49:28 +0300 | [diff] [blame] | 84 | if ((flags & SPI_CONTROLLER_NO_RX) == 0) |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 85 | word |= (getmiso(data) << 31); |
| 86 | |
| 87 | setsck(data, !cpol); |
| 88 | usleep_range(usecs, usecs + 1); |
| 89 | |
| 90 | setsck(data, cpol); |
| 91 | } |
| 92 | |
| 93 | word >>= shift; |
| 94 | return word; |
| 95 | } |
| 96 | |
| 97 | static int |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 98 | spi_lp8841_rtc_transfer_one(struct spi_controller *host, |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 99 | struct spi_device *spi, |
| 100 | struct spi_transfer *t) |
| 101 | { |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 102 | struct spi_lp8841_rtc *data = spi_controller_get_devdata(host); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 103 | unsigned count = t->len; |
| 104 | const u8 *tx = t->tx_buf; |
| 105 | u8 *rx = t->rx_buf; |
| 106 | u8 word = 0; |
| 107 | int ret = 0; |
| 108 | |
| 109 | if (tx) { |
| 110 | data->state &= ~SPI_LP8841_RTC_nWE; |
| 111 | writeb(data->state, data->iomem); |
| 112 | while (likely(count > 0)) { |
| 113 | word = *tx++; |
| 114 | bitbang_txrx_be_cpha0_lsb(data, 1, 0, |
Andy Shevchenko | c397f09 | 2023-07-10 18:49:28 +0300 | [diff] [blame] | 115 | SPI_CONTROLLER_NO_RX, word, 8); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 116 | count--; |
| 117 | } |
| 118 | } else if (rx) { |
| 119 | data->state |= SPI_LP8841_RTC_nWE; |
| 120 | writeb(data->state, data->iomem); |
| 121 | while (likely(count > 0)) { |
| 122 | word = bitbang_txrx_be_cpha0_lsb(data, 1, 0, |
Andy Shevchenko | c397f09 | 2023-07-10 18:49:28 +0300 | [diff] [blame] | 123 | SPI_CONTROLLER_NO_TX, word, 8); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 124 | *rx++ = word; |
| 125 | count--; |
| 126 | } |
| 127 | } else { |
| 128 | ret = -EINVAL; |
| 129 | } |
| 130 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 131 | spi_finalize_current_transfer(host); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 132 | |
| 133 | return ret; |
| 134 | } |
| 135 | |
| 136 | static void |
| 137 | spi_lp8841_rtc_set_cs(struct spi_device *spi, bool enable) |
| 138 | { |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 139 | struct spi_lp8841_rtc *data = spi_controller_get_devdata(spi->controller); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 140 | |
| 141 | data->state = 0; |
| 142 | writeb(data->state, data->iomem); |
| 143 | if (enable) { |
| 144 | usleep_range(4, 5); |
| 145 | data->state |= SPI_LP8841_RTC_CE; |
| 146 | writeb(data->state, data->iomem); |
| 147 | usleep_range(4, 5); |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | static int |
| 152 | spi_lp8841_rtc_setup(struct spi_device *spi) |
| 153 | { |
| 154 | if ((spi->mode & SPI_CS_HIGH) == 0) { |
| 155 | dev_err(&spi->dev, "unsupported active low chip select\n"); |
| 156 | return -EINVAL; |
| 157 | } |
| 158 | |
| 159 | if ((spi->mode & SPI_LSB_FIRST) == 0) { |
| 160 | dev_err(&spi->dev, "unsupported MSB first mode\n"); |
| 161 | return -EINVAL; |
| 162 | } |
| 163 | |
| 164 | if ((spi->mode & SPI_3WIRE) == 0) { |
| 165 | dev_err(&spi->dev, "unsupported wiring. 3 wires required\n"); |
| 166 | return -EINVAL; |
| 167 | } |
| 168 | |
| 169 | return 0; |
| 170 | } |
| 171 | |
| 172 | #ifdef CONFIG_OF |
| 173 | static const struct of_device_id spi_lp8841_rtc_dt_ids[] = { |
| 174 | { .compatible = "icpdas,lp8841-spi-rtc" }, |
| 175 | { } |
| 176 | }; |
| 177 | |
| 178 | MODULE_DEVICE_TABLE(of, spi_lp8841_rtc_dt_ids); |
| 179 | #endif |
| 180 | |
| 181 | static int |
| 182 | spi_lp8841_rtc_probe(struct platform_device *pdev) |
| 183 | { |
| 184 | int ret; |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 185 | struct spi_controller *host; |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 186 | struct spi_lp8841_rtc *data; |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 187 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 188 | host = spi_alloc_host(&pdev->dev, sizeof(*data)); |
| 189 | if (!host) |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 190 | return -ENOMEM; |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 191 | platform_set_drvdata(pdev, host); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 192 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 193 | host->flags = SPI_CONTROLLER_HALF_DUPLEX; |
| 194 | host->mode_bits = SPI_CS_HIGH | SPI_3WIRE | SPI_LSB_FIRST; |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 195 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 196 | host->bus_num = pdev->id; |
| 197 | host->num_chipselect = 1; |
| 198 | host->setup = spi_lp8841_rtc_setup; |
| 199 | host->set_cs = spi_lp8841_rtc_set_cs; |
| 200 | host->transfer_one = spi_lp8841_rtc_transfer_one; |
| 201 | host->bits_per_word_mask = SPI_BPW_MASK(8); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 202 | #ifdef CONFIG_OF |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 203 | host->dev.of_node = pdev->dev.of_node; |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 204 | #endif |
| 205 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 206 | data = spi_controller_get_devdata(host); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 207 | |
YueHaibing | 7d2600b | 2019-09-04 21:58:56 +0800 | [diff] [blame] | 208 | data->iomem = devm_platform_ioremap_resource(pdev, 0); |
Arnd Bergmann | 14a2042 | 2016-02-25 12:37:40 +0100 | [diff] [blame] | 209 | ret = PTR_ERR_OR_ZERO(data->iomem); |
| 210 | if (ret) { |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 211 | dev_err(&pdev->dev, "failed to get IO address\n"); |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 212 | goto err_put_host; |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 213 | } |
| 214 | |
| 215 | /* register with the SPI framework */ |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 216 | ret = devm_spi_register_controller(&pdev->dev, host); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 217 | if (ret) { |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 218 | dev_err(&pdev->dev, "cannot register spi host\n"); |
| 219 | goto err_put_host; |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 220 | } |
| 221 | |
| 222 | return ret; |
| 223 | |
| 224 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 225 | err_put_host: |
| 226 | spi_controller_put(host); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 227 | |
| 228 | return ret; |
| 229 | } |
| 230 | |
| 231 | MODULE_ALIAS("platform:" DRIVER_NAME); |
| 232 | |
| 233 | static struct platform_driver spi_lp8841_rtc_driver = { |
| 234 | .driver = { |
| 235 | .name = DRIVER_NAME, |
| 236 | .of_match_table = of_match_ptr(spi_lp8841_rtc_dt_ids), |
| 237 | }, |
| 238 | .probe = spi_lp8841_rtc_probe, |
| 239 | }; |
| 240 | module_platform_driver(spi_lp8841_rtc_driver); |
| 241 | |
Yang Yingliang | 4881583 | 2023-08-23 11:29:44 +0800 | [diff] [blame] | 242 | MODULE_DESCRIPTION("SPI host driver for ICP DAS LP-8841 RTC"); |
Sergei Ianovich | 7ecbfff | 2016-02-23 13:44:28 +0300 | [diff] [blame] | 243 | MODULE_AUTHOR("Sergei Ianovich"); |
| 244 | MODULE_LICENSE("GPL"); |