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 27 struct xtfpga_spi { 28 struct spi_bitbang bitbang; 29 void __iomem *regs; 30 u32 data; 31 unsigned data_sz; 32 }; 33 34 static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi, 35 unsigned addr, u32 val) 36 { 37 iowrite32(val, spi->regs + addr); 38 } 39 40 static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi, 41 unsigned addr) 42 { 43 return ioread32(spi->regs + addr); 44 } 45 46 static 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 55 static 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 74 static 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 82 static 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; 131 err: 132 spi_master_put(master); 133 return ret; 134 } 135 136 static 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 } 146 147 MODULE_ALIAS("platform:" XTFPGA_SPI_NAME); 148 149 #ifdef CONFIG_OF 150 static const struct of_device_id xtfpga_spi_of_match[] = { 151 { .compatible = "cdns,xtfpga-spi", }, 152 {} 153 }; 154 MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match); 155 #endif 156 157 static 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 }; 166 module_platform_driver(xtfpga_spi_driver); 167 168 MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>"); 169 MODULE_DESCRIPTION("xtensa xtfpga SPI driver"); 170 MODULE_LICENSE("GPL"); 171