drivers/spi/spi-xtensa-xtfpga.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Xtensa xtfpga SPI controller driver
   4  *
   5  * Copyright (c) 2014 Cadence Design Systems Inc.
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/io.h>
  10 #include <linux/module.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/spi/spi.h>
  14 #include <linux/spi/spi_bitbang.h>
  15
  16 #define XTFPGA_SPI_NAME "xtfpga_spi"
  17
  18 #define XTFPGA_SPI_START        0x0
  19 #define XTFPGA_SPI_BUSY         0x4
  20 #define XTFPGA_SPI_DATA         0x8
  21
  22 #define BUSY_WAIT_US            100
  23
  24 struct xtfpga_spi {
  25         struct spi_bitbang bitbang;
  26         void __iomem *regs;
  27         u32 data;
  28         unsigned data_sz;
  29 };
  30
  31 static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi,
  32                                       unsigned addr, u32 val)
  33 {
  34         __raw_writel(val, spi->regs + addr);
  35 }
  36
  37 static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi,
  38                                              unsigned addr)
  39 {
  40         return __raw_readl(spi->regs + addr);
  41 }
  42
  43 static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi)
  44 {
  45         unsigned i;
  46
  47         for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) &&
  48              i < BUSY_WAIT_US; ++i)
  49                 udelay(1);
  50         WARN_ON_ONCE(i == BUSY_WAIT_US);
  51 }
  52
  53 static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
  54                                 u32 v, u8 bits, unsigned flags)
  55 {
  56         struct xtfpga_spi *xspi = spi_controller_get_devdata(spi->controller);
  57
  58         xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0));
  59         xspi->data_sz += bits;
  60         if (xspi->data_sz >= 16) {
  61                 xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA,
  62                                    xspi->data >> (xspi->data_sz - 16));
  63                 xspi->data_sz -= 16;
  64                 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1);
  65                 xtfpga_spi_wait_busy(xspi);
  66                 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
  67         }
  68
  69         return 0;
  70 }
  71
  72 static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on)
  73 {
  74         struct xtfpga_spi *xspi = spi_controller_get_devdata(spi->controller);
  75
  76         WARN_ON(xspi->data_sz != 0);
  77         xspi->data_sz = 0;
  78 }
  79
  80 static int xtfpga_spi_probe(struct platform_device *pdev)
  81 {
  82         struct xtfpga_spi *xspi;
  83         int ret;
  84         struct spi_controller *host;
  85
  86         host = devm_spi_alloc_host(&pdev->dev, sizeof(struct xtfpga_spi));
  87         if (!host)
  88                 return -ENOMEM;
  89
  90         host->flags = SPI_CONTROLLER_NO_RX;
  91         host->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
  92         host->bus_num = pdev->dev.id;
  93         host->dev.of_node = pdev->dev.of_node;
  94
  95         xspi = spi_controller_get_devdata(host);
  96         xspi->bitbang.ctlr = host;
  97         xspi->bitbang.chipselect = xtfpga_spi_chipselect;
  98         xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word;
  99         xspi->regs = devm_platform_ioremap_resource(pdev, 0);
 100         if (IS_ERR(xspi->regs))
 101                 return PTR_ERR(xspi->regs);
 102
 103         xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
 104         usleep_range(1000, 2000);
 105         if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) {
 106                 dev_err(&pdev->dev, "Device stuck in busy state\n");
 107                 return -EBUSY;
 108         }
 109
 110         ret = spi_bitbang_start(&xspi->bitbang);
 111         if (ret < 0) {
 112                 dev_err(&pdev->dev, "spi_bitbang_start failed\n");
 113                 return ret;
 114         }
 115
 116         platform_set_drvdata(pdev, host);
 117         return 0;
 118 }
 119
 120 static void xtfpga_spi_remove(struct platform_device *pdev)
 121 {
 122         struct spi_controller *host = platform_get_drvdata(pdev);
 123         struct xtfpga_spi *xspi = spi_controller_get_devdata(host);
 124
 125         spi_bitbang_stop(&xspi->bitbang);
 126         spi_controller_put(host);
 127 }
 128
 129 MODULE_ALIAS("platform:" XTFPGA_SPI_NAME);
 130
 131 #ifdef CONFIG_OF
 132 static const struct of_device_id xtfpga_spi_of_match[] = {
 133         { .compatible = "cdns,xtfpga-spi", },
 134         {}
 135 };
 136 MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match);
 137 #endif
 138
 139 static struct platform_driver xtfpga_spi_driver = {
 140         .probe = xtfpga_spi_probe,
 141         .remove = xtfpga_spi_remove,
 142         .driver = {
 143                 .name = XTFPGA_SPI_NAME,
 144                 .of_match_table = of_match_ptr(xtfpga_spi_of_match),
 145         },
 146 };
 147 module_platform_driver(xtfpga_spi_driver);
 148
 149 MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
 150 MODULE_DESCRIPTION("xtensa xtfpga SPI driver");
 151 MODULE_LICENSE("GPL");