linux/drivers/spi/spi-xtensa-xtfpga.c
<<
>>
Prefs
   1/*
   2 * Xtensa xtfpga SPI controller driver
   3 *
   4 * Copyright (c) 2014 Cadence Design Systems Inc.
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 */
  10
  11#include <linux/delay.h>
  12#include <linux/io.h>
  13#include <linux/module.h>
  14#include <linux/of.h>
  15#include <linux/platform_device.h>
  16#include <linux/spi/spi.h>
  17#include <linux/spi/spi_bitbang.h>
  18
  19#define XTFPGA_SPI_NAME "xtfpga_spi"
  20
  21#define XTFPGA_SPI_START        0x0
  22#define XTFPGA_SPI_BUSY         0x4
  23#define XTFPGA_SPI_DATA         0x8
  24
  25#define BUSY_WAIT_US            100
  26
  27struct xtfpga_spi {
  28        struct spi_bitbang bitbang;
  29        void __iomem *regs;
  30        u32 data;
  31        unsigned data_sz;
  32};
  33
  34static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi,
  35                                      unsigned addr, u32 val)
  36{
  37        iowrite32(val, spi->regs + addr);
  38}
  39
  40static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi,
  41                                             unsigned addr)
  42{
  43        return ioread32(spi->regs + addr);
  44}
  45
  46static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi)
  47{
  48        unsigned i;
  49        for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) &&
  50             i < BUSY_WAIT_US; ++i)
  51                udelay(1);
  52        WARN_ON_ONCE(i == BUSY_WAIT_US);
  53}
  54
  55static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
  56                                u32 v, u8 bits)
  57{
  58        struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
  59
  60        xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0));
  61        xspi->data_sz += bits;
  62        if (xspi->data_sz >= 16) {
  63                xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA,
  64                                   xspi->data >> (xspi->data_sz - 16));
  65                xspi->data_sz -= 16;
  66                xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1);
  67                xtfpga_spi_wait_busy(xspi);
  68                xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
  69        }
  70
  71        return 0;
  72}
  73
  74static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on)
  75{
  76        struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
  77
  78        WARN_ON(xspi->data_sz != 0);
  79        xspi->data_sz = 0;
  80}
  81
  82static int xtfpga_spi_probe(struct platform_device *pdev)
  83{
  84        struct xtfpga_spi *xspi;
  85        struct resource *mem;
  86        int ret;
  87        struct spi_master *master;
  88
  89        master = spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi));
  90        if (!master)
  91                return -ENOMEM;
  92
  93        master->flags = SPI_MASTER_NO_RX;
  94        master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
  95        master->bus_num = pdev->dev.id;
  96        master->dev.of_node = pdev->dev.of_node;
  97
  98        xspi = spi_master_get_devdata(master);
  99        xspi->bitbang.master = master;
 100        xspi->bitbang.chipselect = xtfpga_spi_chipselect;
 101        xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word;
 102
 103        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 104        if (!mem) {
 105                dev_err(&pdev->dev, "No memory resource\n");
 106                ret = -ENODEV;
 107                goto err;
 108        }
 109        xspi->regs = devm_ioremap_resource(&pdev->dev, mem);
 110        if (IS_ERR(xspi->regs)) {
 111                ret = PTR_ERR(xspi->regs);
 112                goto err;
 113        }
 114
 115        xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
 116        usleep_range(1000, 2000);
 117        if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) {
 118                dev_err(&pdev->dev, "Device stuck in busy state\n");
 119                ret = -EBUSY;
 120                goto err;
 121        }
 122
 123        ret = spi_bitbang_start(&xspi->bitbang);
 124        if (ret < 0) {
 125                dev_err(&pdev->dev, "spi_bitbang_start failed\n");
 126                goto err;
 127        }
 128
 129        platform_set_drvdata(pdev, master);
 130        return 0;
 131err:
 132        spi_master_put(master);
 133        return ret;
 134}
 135
 136static int xtfpga_spi_remove(struct platform_device *pdev)
 137{
 138        struct spi_master *master = platform_get_drvdata(pdev);
 139        struct xtfpga_spi *xspi = spi_master_get_devdata(master);
 140
 141        spi_bitbang_stop(&xspi->bitbang);
 142        spi_master_put(master);
 143
 144        return 0;
 145}
 146
 147MODULE_ALIAS("platform:" XTFPGA_SPI_NAME);
 148
 149#ifdef CONFIG_OF
 150static const struct of_device_id xtfpga_spi_of_match[] = {
 151        { .compatible = "cdns,xtfpga-spi", },
 152        {}
 153};
 154MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match);
 155#endif
 156
 157static struct platform_driver xtfpga_spi_driver = {
 158        .probe = xtfpga_spi_probe,
 159        .remove = xtfpga_spi_remove,
 160        .driver = {
 161                .name = XTFPGA_SPI_NAME,
 162                .owner = THIS_MODULE,
 163                .of_match_table = of_match_ptr(xtfpga_spi_of_match),
 164        },
 165};
 166module_platform_driver(xtfpga_spi_driver);
 167
 168MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
 169MODULE_DESCRIPTION("xtensa xtfpga SPI driver");
 170MODULE_LICENSE("GPL");
 171
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.