1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * SPI controller driver for the Mikrotik RB4xx boards 4 * 5 * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org> 6 * Copyright (C) 2015 Bert Vermeulen <bert@biot.com> 7 * 8 * This file was based on the patches for Linux 2.6.27.39 published by 9 * MikroTik for their RouterBoard 4xx series devices. 10 */ 11 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/platform_device.h> 15 #include <linux/clk.h> 16 #include <linux/spi/spi.h> 17 18 #include <asm/mach-ath79/ar71xx_regs.h> 19 20 struct rb4xx_spi { 21 void __iomem *base; 22 struct clk *clk; 23 }; 24 25 static inline u32 rb4xx_read(struct rb4xx_spi *rbspi, u32 reg) 26 { 27 return __raw_readl(rbspi->base + reg); 28 } 29 30 static inline void rb4xx_write(struct rb4xx_spi *rbspi, u32 reg, u32 value) 31 { 32 __raw_writel(value, rbspi->base + reg); 33 } 34 35 static inline void do_spi_clk(struct rb4xx_spi *rbspi, u32 spi_ioc, int value) 36 { 37 u32 regval; 38 39 regval = spi_ioc; 40 if (value & BIT(0)) 41 regval |= AR71XX_SPI_IOC_DO; 42 43 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval); 44 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK); 45 } 46 47 static void do_spi_byte(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte) 48 { 49 int i; 50 51 for (i = 7; i >= 0; i--) 52 do_spi_clk(rbspi, spi_ioc, byte >> i); 53 } 54 55 /* The CS2 pin is used to clock in a second bit per clock cycle. */ 56 static inline void do_spi_clk_two(struct rb4xx_spi *rbspi, u32 spi_ioc, 57 u8 value) 58 { 59 u32 regval; 60 61 regval = spi_ioc; 62 if (value & BIT(1)) 63 regval |= AR71XX_SPI_IOC_DO; 64 if (value & BIT(0)) 65 regval |= AR71XX_SPI_IOC_CS2; 66 67 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval); 68 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK); 69 } 70 71 /* Two bits at a time, msb first */ 72 static void do_spi_byte_two(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte) 73 { 74 do_spi_clk_two(rbspi, spi_ioc, byte >> 6); 75 do_spi_clk_two(rbspi, spi_ioc, byte >> 4); 76 do_spi_clk_two(rbspi, spi_ioc, byte >> 2); 77 do_spi_clk_two(rbspi, spi_ioc, byte >> 0); 78 } 79 80 static void rb4xx_set_cs(struct spi_device *spi, bool enable) 81 { 82 struct rb4xx_spi *rbspi = spi_master_get_devdata(spi->master); 83 84 /* 85 * Setting CS is done along with bitbanging the actual values, 86 * since it's all on the same hardware register. However the 87 * CPLD needs CS deselected after every command. 88 */ 89 if (enable) 90 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, 91 AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1); 92 } 93 94 static int rb4xx_transfer_one(struct spi_master *master, 95 struct spi_device *spi, struct spi_transfer *t) 96 { 97 struct rb4xx_spi *rbspi = spi_master_get_devdata(master); 98 int i; 99 u32 spi_ioc; 100 u8 *rx_buf; 101 const u8 *tx_buf; 102 103 /* 104 * Prime the SPI register with the SPI device selected. The m25p80 boot 105 * flash and CPLD share the CS0 pin. This works because the CPLD's 106 * command set was designed to almost not clash with that of the 107 * boot flash. 108 */ 109 if (spi->chip_select == 2) 110 /* MMC */ 111 spi_ioc = AR71XX_SPI_IOC_CS0; 112 else 113 /* Boot flash and CPLD */ 114 spi_ioc = AR71XX_SPI_IOC_CS1; 115 116 tx_buf = t->tx_buf; 117 rx_buf = t->rx_buf; 118 for (i = 0; i < t->len; ++i) { 119 if (t->tx_nbits == SPI_NBITS_DUAL) 120 /* CPLD can use two-wire transfers */ 121 do_spi_byte_two(rbspi, spi_ioc, tx_buf[i]); 122 else 123 do_spi_byte(rbspi, spi_ioc, tx_buf[i]); 124 if (!rx_buf) 125 continue; 126 rx_buf[i] = rb4xx_read(rbspi, AR71XX_SPI_REG_RDS); 127 } 128 spi_finalize_current_transfer(master); 129 130 return 0; 131 } 132 133 static int rb4xx_spi_probe(struct platform_device *pdev) 134 { 135 struct spi_master *master; 136 struct clk *ahb_clk; 137 struct rb4xx_spi *rbspi; 138 struct resource *r; 139 int err; 140 void __iomem *spi_base; 141 142 r = platform_get_resource(pdev, IORESOURCE_MEM, 0); 143 spi_base = devm_ioremap_resource(&pdev->dev, r); 144 if (IS_ERR(spi_base)) 145 return PTR_ERR(spi_base); 146 147 master = spi_alloc_master(&pdev->dev, sizeof(*rbspi)); 148 if (!master) 149 return -ENOMEM; 150 151 ahb_clk = devm_clk_get(&pdev->dev, "ahb"); 152 if (IS_ERR(ahb_clk)) 153 return PTR_ERR(ahb_clk); 154 155 master->bus_num = 0; 156 master->num_chipselect = 3; 157 master->mode_bits = SPI_TX_DUAL; 158 master->bits_per_word_mask = SPI_BPW_MASK(8); 159 master->flags = SPI_MASTER_MUST_TX; 160 master->transfer_one = rb4xx_transfer_one; 161 master->set_cs = rb4xx_set_cs; 162 163 err = devm_spi_register_master(&pdev->dev, master); 164 if (err) { 165 dev_err(&pdev->dev, "failed to register SPI master\n"); 166 return err; 167 } 168 169 err = clk_prepare_enable(ahb_clk); 170 if (err) 171 return err; 172 173 rbspi = spi_master_get_devdata(master); 174 rbspi->base = spi_base; 175 rbspi->clk = ahb_clk; 176 platform_set_drvdata(pdev, rbspi); 177 178 /* Enable SPI */ 179 rb4xx_write(rbspi, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO); 180 181 return 0; 182 } 183 184 static int rb4xx_spi_remove(struct platform_device *pdev) 185 { 186 struct rb4xx_spi *rbspi = platform_get_drvdata(pdev); 187 188 clk_disable_unprepare(rbspi->clk); 189 190 return 0; 191 } 192 193 static struct platform_driver rb4xx_spi_drv = { 194 .probe = rb4xx_spi_probe, 195 .remove = rb4xx_spi_remove, 196 .driver = { 197 .name = "rb4xx-spi", 198 }, 199 }; 200 201 module_platform_driver(rb4xx_spi_drv); 202 203 MODULE_DESCRIPTION("Mikrotik RB4xx SPI controller driver"); 204 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); 205 MODULE_AUTHOR("Bert Vermeulen <bert@biot.com>"); 206 MODULE_LICENSE("GPL v2"); 207