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 #include <linux/of.h> 18 19 #include <asm/mach-ath79/ar71xx_regs.h> 20 21 struct rb4xx_spi { 22 void __iomem *base; 23 struct clk *clk; 24 }; 25 26 static inline u32 rb4xx_read(struct rb4xx_spi *rbspi, u32 reg) 27 { 28 return __raw_readl(rbspi->base + reg); 29 } 30 31 static inline void rb4xx_write(struct rb4xx_spi *rbspi, u32 reg, u32 value) 32 { 33 __raw_writel(value, rbspi->base + reg); 34 } 35 36 static inline void do_spi_clk(struct rb4xx_spi *rbspi, u32 spi_ioc, int value) 37 { 38 u32 regval; 39 40 regval = spi_ioc; 41 if (value & BIT(0)) 42 regval |= AR71XX_SPI_IOC_DO; 43 44 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval); 45 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK); 46 } 47 48 static void do_spi_byte(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte) 49 { 50 int i; 51 52 for (i = 7; i >= 0; i--) 53 do_spi_clk(rbspi, spi_ioc, byte >> i); 54 } 55 56 /* The CS2 pin is used to clock in a second bit per clock cycle. */ 57 static inline void do_spi_clk_two(struct rb4xx_spi *rbspi, u32 spi_ioc, 58 u8 value) 59 { 60 u32 regval; 61 62 regval = spi_ioc; 63 if (value & BIT(1)) 64 regval |= AR71XX_SPI_IOC_DO; 65 if (value & BIT(0)) 66 regval |= AR71XX_SPI_IOC_CS2; 67 68 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval); 69 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK); 70 } 71 72 /* Two bits at a time, msb first */ 73 static void do_spi_byte_two(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte) 74 { 75 do_spi_clk_two(rbspi, spi_ioc, byte >> 6); 76 do_spi_clk_two(rbspi, spi_ioc, byte >> 4); 77 do_spi_clk_two(rbspi, spi_ioc, byte >> 2); 78 do_spi_clk_two(rbspi, spi_ioc, byte >> 0); 79 } 80 81 static void rb4xx_set_cs(struct spi_device *spi, bool enable) 82 { 83 struct rb4xx_spi *rbspi = spi_master_get_devdata(spi->master); 84 85 /* 86 * Setting CS is done along with bitbanging the actual values, 87 * since it's all on the same hardware register. However the 88 * CPLD needs CS deselected after every command. 89 */ 90 if (enable) 91 rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, 92 AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1); 93 } 94 95 static int rb4xx_transfer_one(struct spi_master *master, 96 struct spi_device *spi, struct spi_transfer *t) 97 { 98 struct rb4xx_spi *rbspi = spi_master_get_devdata(master); 99 int i; 100 u32 spi_ioc; 101 u8 *rx_buf; 102 const u8 *tx_buf; 103 104 /* 105 * Prime the SPI register with the SPI device selected. The m25p80 boot 106 * flash and CPLD share the CS0 pin. This works because the CPLD's 107 * command set was designed to almost not clash with that of the 108 * boot flash. 109 */ 110 if (spi->chip_select == 2) 111 /* MMC */ 112 spi_ioc = AR71XX_SPI_IOC_CS0; 113 else 114 /* Boot flash and CPLD */ 115 spi_ioc = AR71XX_SPI_IOC_CS1; 116 117 tx_buf = t->tx_buf; 118 rx_buf = t->rx_buf; 119 for (i = 0; i < t->len; ++i) { 120 if (t->tx_nbits == SPI_NBITS_DUAL) 121 /* CPLD can use two-wire transfers */ 122 do_spi_byte_two(rbspi, spi_ioc, tx_buf[i]); 123 else 124 do_spi_byte(rbspi, spi_ioc, tx_buf[i]); 125 if (!rx_buf) 126 continue; 127 rx_buf[i] = rb4xx_read(rbspi, AR71XX_SPI_REG_RDS); 128 } 129 spi_finalize_current_transfer(master); 130 131 return 0; 132 } 133 134 static int rb4xx_spi_probe(struct platform_device *pdev) 135 { 136 struct spi_master *master; 137 struct clk *ahb_clk; 138 struct rb4xx_spi *rbspi; 139 int err; 140 void __iomem *spi_base; 141 142 spi_base = devm_platform_ioremap_resource(pdev, 0); 143 if (IS_ERR(spi_base)) 144 return PTR_ERR(spi_base); 145 146 master = devm_spi_alloc_master(&pdev->dev, sizeof(*rbspi)); 147 if (!master) 148 return -ENOMEM; 149 150 ahb_clk = devm_clk_get(&pdev->dev, "ahb"); 151 if (IS_ERR(ahb_clk)) 152 return PTR_ERR(ahb_clk); 153 154 master->dev.of_node = pdev->dev.of_node; 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 rbspi = spi_master_get_devdata(master); 164 rbspi->base = spi_base; 165 rbspi->clk = ahb_clk; 166 platform_set_drvdata(pdev, rbspi); 167 168 err = devm_spi_register_master(&pdev->dev, master); 169 if (err) { 170 dev_err(&pdev->dev, "failed to register SPI master\n"); 171 return err; 172 } 173 174 err = clk_prepare_enable(ahb_clk); 175 if (err) 176 return err; 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 const struct of_device_id rb4xx_spi_dt_match[] = { 194 { .compatible = "mikrotik,rb4xx-spi" }, 195 { }, 196 }; 197 MODULE_DEVICE_TABLE(of, rb4xx_spi_dt_match); 198 199 static struct platform_driver rb4xx_spi_drv = { 200 .probe = rb4xx_spi_probe, 201 .remove = rb4xx_spi_remove, 202 .driver = { 203 .name = "rb4xx-spi", 204 .of_match_table = of_match_ptr(rb4xx_spi_dt_match), 205 }, 206 }; 207 208 module_platform_driver(rb4xx_spi_drv); 209 210 MODULE_DESCRIPTION("Mikrotik RB4xx SPI controller driver"); 211 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); 212 MODULE_AUTHOR("Bert Vermeulen <bert@biot.com>"); 213 MODULE_LICENSE("GPL v2"); 214