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 __raw_writel(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 __raw_readl(spi->regs + addr); 44 } 45 46 static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi) 47 { 48 unsigned i; 49 50 for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) && 51 i < BUSY_WAIT_US; ++i) 52 udelay(1); 53 WARN_ON_ONCE(i == BUSY_WAIT_US); 54 } 55 56 static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs, 57 u32 v, u8 bits, unsigned flags) 58 { 59 struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master); 60 61 xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0)); 62 xspi->data_sz += bits; 63 if (xspi->data_sz >= 16) { 64 xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA, 65 xspi->data >> (xspi->data_sz - 16)); 66 xspi->data_sz -= 16; 67 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1); 68 xtfpga_spi_wait_busy(xspi); 69 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0); 70 } 71 72 return 0; 73 } 74 75 static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on) 76 { 77 struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master); 78 79 WARN_ON(xspi->data_sz != 0); 80 xspi->data_sz = 0; 81 } 82 83 static int xtfpga_spi_probe(struct platform_device *pdev) 84 { 85 struct xtfpga_spi *xspi; 86 struct resource *mem; 87 int ret; 88 struct spi_master *master; 89 90 master = spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi)); 91 if (!master) 92 return -ENOMEM; 93 94 master->flags = SPI_MASTER_NO_RX; 95 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16); 96 master->bus_num = pdev->dev.id; 97 master->dev.of_node = pdev->dev.of_node; 98 99 xspi = spi_master_get_devdata(master); 100 xspi->bitbang.master = master; 101 xspi->bitbang.chipselect = xtfpga_spi_chipselect; 102 xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word; 103 104 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); 105 if (!mem) { 106 dev_err(&pdev->dev, "No memory resource\n"); 107 ret = -ENODEV; 108 goto err; 109 } 110 xspi->regs = devm_ioremap_resource(&pdev->dev, mem); 111 if (IS_ERR(xspi->regs)) { 112 ret = PTR_ERR(xspi->regs); 113 goto err; 114 } 115 116 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0); 117 usleep_range(1000, 2000); 118 if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) { 119 dev_err(&pdev->dev, "Device stuck in busy state\n"); 120 ret = -EBUSY; 121 goto err; 122 } 123 124 ret = spi_bitbang_start(&xspi->bitbang); 125 if (ret < 0) { 126 dev_err(&pdev->dev, "spi_bitbang_start failed\n"); 127 goto err; 128 } 129 130 platform_set_drvdata(pdev, master); 131 return 0; 132 err: 133 spi_master_put(master); 134 return ret; 135 } 136 137 static int xtfpga_spi_remove(struct platform_device *pdev) 138 { 139 struct spi_master *master = platform_get_drvdata(pdev); 140 struct xtfpga_spi *xspi = spi_master_get_devdata(master); 141 142 spi_bitbang_stop(&xspi->bitbang); 143 spi_master_put(master); 144 145 return 0; 146 } 147 148 MODULE_ALIAS("platform:" XTFPGA_SPI_NAME); 149 150 #ifdef CONFIG_OF 151 static const struct of_device_id xtfpga_spi_of_match[] = { 152 { .compatible = "cdns,xtfpga-spi", }, 153 {} 154 }; 155 MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match); 156 #endif 157 158 static struct platform_driver xtfpga_spi_driver = { 159 .probe = xtfpga_spi_probe, 160 .remove = xtfpga_spi_remove, 161 .driver = { 162 .name = XTFPGA_SPI_NAME, 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