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_master_get_devdata(spi->master); 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_master_get_devdata(spi->master); 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_master *master; 85 86 master = devm_spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi)); 87 if (!master) 88 return -ENOMEM; 89 90 master->flags = SPI_CONTROLLER_NO_RX; 91 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16); 92 master->bus_num = pdev->dev.id; 93 master->dev.of_node = pdev->dev.of_node; 94 95 xspi = spi_master_get_devdata(master); 96 xspi->bitbang.master = master; 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, master); 117 return 0; 118 } 119 120 static void xtfpga_spi_remove(struct platform_device *pdev) 121 { 122 struct spi_master *master = platform_get_drvdata(pdev); 123 struct xtfpga_spi *xspi = spi_master_get_devdata(master); 124 125 spi_bitbang_stop(&xspi->bitbang); 126 spi_master_put(master); 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_new = 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"); 152