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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * OpenCores tiny SPI host driver4 *5 * https://opencores.org/project,tiny_spi6 *7 * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>8 *9 * Based on spi_s3c24xx.c, which is:10 * Copyright (c) 2006 Ben Dooks11 * Copyright (c) 2006 Simtec Electronics12 * Ben Dooks <ben@simtec.co.uk>13 */14 15#include <linux/interrupt.h>16#include <linux/errno.h>17#include <linux/module.h>18#include <linux/platform_device.h>19#include <linux/spi/spi.h>20#include <linux/spi/spi_bitbang.h>21#include <linux/spi/spi_oc_tiny.h>22#include <linux/io.h>23#include <linux/of.h>24 25#define DRV_NAME "spi_oc_tiny"26 27#define TINY_SPI_RXDATA 028#define TINY_SPI_TXDATA 429#define TINY_SPI_STATUS 830#define TINY_SPI_CONTROL 1231#define TINY_SPI_BAUD 1632 33#define TINY_SPI_STATUS_TXE 0x134#define TINY_SPI_STATUS_TXR 0x235 36struct tiny_spi {37 /* bitbang has to be first */38 struct spi_bitbang bitbang;39 struct completion done;40 41 void __iomem *base;42 int irq;43 unsigned int freq;44 unsigned int baudwidth;45 unsigned int baud;46 unsigned int speed_hz;47 unsigned int mode;48 unsigned int len;49 unsigned int txc, rxc;50 const u8 *txp;51 u8 *rxp;52};53 54static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)55{56 return spi_controller_get_devdata(sdev->controller);57}58 59static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)60{61 struct tiny_spi *hw = tiny_spi_to_hw(spi);62 63 return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;64}65 66static int tiny_spi_setup_transfer(struct spi_device *spi,67 struct spi_transfer *t)68{69 struct tiny_spi *hw = tiny_spi_to_hw(spi);70 unsigned int baud = hw->baud;71 72 if (t) {73 if (t->speed_hz && t->speed_hz != hw->speed_hz)74 baud = tiny_spi_baud(spi, t->speed_hz);75 }76 writel(baud, hw->base + TINY_SPI_BAUD);77 writel(hw->mode, hw->base + TINY_SPI_CONTROL);78 return 0;79}80 81static int tiny_spi_setup(struct spi_device *spi)82{83 struct tiny_spi *hw = tiny_spi_to_hw(spi);84 85 if (spi->max_speed_hz != hw->speed_hz) {86 hw->speed_hz = spi->max_speed_hz;87 hw->baud = tiny_spi_baud(spi, hw->speed_hz);88 }89 hw->mode = spi->mode & SPI_MODE_X_MASK;90 return 0;91}92 93static inline void tiny_spi_wait_txr(struct tiny_spi *hw)94{95 while (!(readb(hw->base + TINY_SPI_STATUS) &96 TINY_SPI_STATUS_TXR))97 cpu_relax();98}99 100static inline void tiny_spi_wait_txe(struct tiny_spi *hw)101{102 while (!(readb(hw->base + TINY_SPI_STATUS) &103 TINY_SPI_STATUS_TXE))104 cpu_relax();105}106 107static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)108{109 struct tiny_spi *hw = tiny_spi_to_hw(spi);110 const u8 *txp = t->tx_buf;111 u8 *rxp = t->rx_buf;112 unsigned int i;113 114 if (hw->irq >= 0) {115 /* use interrupt driven data transfer */116 hw->len = t->len;117 hw->txp = t->tx_buf;118 hw->rxp = t->rx_buf;119 hw->txc = 0;120 hw->rxc = 0;121 122 /* send the first byte */123 if (t->len > 1) {124 writeb(hw->txp ? *hw->txp++ : 0,125 hw->base + TINY_SPI_TXDATA);126 hw->txc++;127 writeb(hw->txp ? *hw->txp++ : 0,128 hw->base + TINY_SPI_TXDATA);129 hw->txc++;130 writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);131 } else {132 writeb(hw->txp ? *hw->txp++ : 0,133 hw->base + TINY_SPI_TXDATA);134 hw->txc++;135 writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);136 }137 138 wait_for_completion(&hw->done);139 } else {140 /* we need to tighten the transfer loop */141 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);142 for (i = 1; i < t->len; i++) {143 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);144 145 if (rxp || (i != t->len - 1))146 tiny_spi_wait_txr(hw);147 if (rxp)148 *rxp++ = readb(hw->base + TINY_SPI_TXDATA);149 }150 tiny_spi_wait_txe(hw);151 if (rxp)152 *rxp++ = readb(hw->base + TINY_SPI_RXDATA);153 }154 155 return t->len;156}157 158static irqreturn_t tiny_spi_irq(int irq, void *dev)159{160 struct tiny_spi *hw = dev;161 162 writeb(0, hw->base + TINY_SPI_STATUS);163 if (hw->rxc + 1 == hw->len) {164 if (hw->rxp)165 *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);166 hw->rxc++;167 complete(&hw->done);168 } else {169 if (hw->rxp)170 *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);171 hw->rxc++;172 if (hw->txc < hw->len) {173 writeb(hw->txp ? *hw->txp++ : 0,174 hw->base + TINY_SPI_TXDATA);175 hw->txc++;176 writeb(TINY_SPI_STATUS_TXR,177 hw->base + TINY_SPI_STATUS);178 } else {179 writeb(TINY_SPI_STATUS_TXE,180 hw->base + TINY_SPI_STATUS);181 }182 }183 return IRQ_HANDLED;184}185 186#ifdef CONFIG_OF187static int tiny_spi_of_probe(struct platform_device *pdev)188{189 struct tiny_spi *hw = platform_get_drvdata(pdev);190 struct device_node *np = pdev->dev.of_node;191 u32 val;192 193 if (!np)194 return 0;195 hw->bitbang.ctlr->dev.of_node = pdev->dev.of_node;196 if (!of_property_read_u32(np, "clock-frequency", &val))197 hw->freq = val;198 if (!of_property_read_u32(np, "baud-width", &val))199 hw->baudwidth = val;200 return 0;201}202#else /* !CONFIG_OF */203static int tiny_spi_of_probe(struct platform_device *pdev)204{205 return 0;206}207#endif /* CONFIG_OF */208 209static int tiny_spi_probe(struct platform_device *pdev)210{211 struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);212 struct tiny_spi *hw;213 struct spi_controller *host;214 int err = -ENODEV;215 216 host = spi_alloc_host(&pdev->dev, sizeof(struct tiny_spi));217 if (!host)218 return err;219 220 /* setup the host state. */221 host->bus_num = pdev->id;222 host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;223 host->setup = tiny_spi_setup;224 host->use_gpio_descriptors = true;225 226 hw = spi_controller_get_devdata(host);227 platform_set_drvdata(pdev, hw);228 229 /* setup the state for the bitbang driver */230 hw->bitbang.ctlr = host;231 hw->bitbang.setup_transfer = tiny_spi_setup_transfer;232 hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;233 234 /* find and map our resources */235 hw->base = devm_platform_ioremap_resource(pdev, 0);236 if (IS_ERR(hw->base)) {237 err = PTR_ERR(hw->base);238 goto exit;239 }240 /* irq is optional */241 hw->irq = platform_get_irq(pdev, 0);242 if (hw->irq >= 0) {243 init_completion(&hw->done);244 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,245 pdev->name, hw);246 if (err)247 goto exit;248 }249 /* find platform data */250 if (platp) {251 hw->freq = platp->freq;252 hw->baudwidth = platp->baudwidth;253 } else {254 err = tiny_spi_of_probe(pdev);255 if (err)256 goto exit;257 }258 259 /* register our spi controller */260 err = spi_bitbang_start(&hw->bitbang);261 if (err)262 goto exit;263 dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);264 265 return 0;266 267exit:268 spi_controller_put(host);269 return err;270}271 272static void tiny_spi_remove(struct platform_device *pdev)273{274 struct tiny_spi *hw = platform_get_drvdata(pdev);275 struct spi_controller *host = hw->bitbang.ctlr;276 277 spi_bitbang_stop(&hw->bitbang);278 spi_controller_put(host);279}280 281#ifdef CONFIG_OF282static const struct of_device_id tiny_spi_match[] = {283 { .compatible = "opencores,tiny-spi-rtlsvn2", },284 {},285};286MODULE_DEVICE_TABLE(of, tiny_spi_match);287#endif /* CONFIG_OF */288 289static struct platform_driver tiny_spi_driver = {290 .probe = tiny_spi_probe,291 .remove_new = tiny_spi_remove,292 .driver = {293 .name = DRV_NAME,294 .pm = NULL,295 .of_match_table = of_match_ptr(tiny_spi_match),296 },297};298module_platform_driver(tiny_spi_driver);299 300MODULE_DESCRIPTION("OpenCores tiny SPI driver");301MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");302MODULE_LICENSE("GPL");303MODULE_ALIAS("platform:" DRV_NAME);304