1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Altera SPI driver 4 * 5 * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw> 6 * 7 * Based on spi_s3c24xx.c, which is: 8 * Copyright (c) 2006 Ben Dooks 9 * Copyright (c) 2006 Simtec Electronics 10 * Ben Dooks <ben@simtec.co.uk> 11 */ 12 13 #include <linux/errno.h> 14 #include <linux/module.h> 15 #include <linux/platform_device.h> 16 #include <linux/spi/altera.h> 17 #include <linux/spi/spi.h> 18 #include <linux/io.h> 19 #include <linux/of.h> 20 21 #define DRV_NAME "spi_altera" 22 23 #define ALTERA_SPI_RXDATA 0 24 #define ALTERA_SPI_TXDATA 4 25 #define ALTERA_SPI_STATUS 8 26 #define ALTERA_SPI_CONTROL 12 27 #define ALTERA_SPI_TARGET_SEL 20 28 29 #define ALTERA_SPI_STATUS_ROE_MSK 0x8 30 #define ALTERA_SPI_STATUS_TOE_MSK 0x10 31 #define ALTERA_SPI_STATUS_TMT_MSK 0x20 32 #define ALTERA_SPI_STATUS_TRDY_MSK 0x40 33 #define ALTERA_SPI_STATUS_RRDY_MSK 0x80 34 #define ALTERA_SPI_STATUS_E_MSK 0x100 35 36 #define ALTERA_SPI_CONTROL_IROE_MSK 0x8 37 #define ALTERA_SPI_CONTROL_ITOE_MSK 0x10 38 #define ALTERA_SPI_CONTROL_ITRDY_MSK 0x40 39 #define ALTERA_SPI_CONTROL_IRRDY_MSK 0x80 40 #define ALTERA_SPI_CONTROL_IE_MSK 0x100 41 #define ALTERA_SPI_CONTROL_SSO_MSK 0x400 42 43 static int altr_spi_writel(struct altera_spi *hw, unsigned int reg, 44 unsigned int val) 45 { 46 int ret; 47 48 ret = regmap_write(hw->regmap, hw->regoff + reg, val); 49 if (ret) 50 dev_err(hw->dev, "fail to write reg 0x%x val 0x%x: %d\n", 51 reg, val, ret); 52 53 return ret; 54 } 55 56 static int altr_spi_readl(struct altera_spi *hw, unsigned int reg, 57 unsigned int *val) 58 { 59 int ret; 60 61 ret = regmap_read(hw->regmap, hw->regoff + reg, val); 62 if (ret) 63 dev_err(hw->dev, "fail to read reg 0x%x: %d\n", reg, ret); 64 65 return ret; 66 } 67 68 static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev) 69 { 70 return spi_controller_get_devdata(sdev->controller); 71 } 72 73 static void altera_spi_set_cs(struct spi_device *spi, bool is_high) 74 { 75 struct altera_spi *hw = altera_spi_to_hw(spi); 76 77 if (is_high) { 78 hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK; 79 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr); 80 altr_spi_writel(hw, ALTERA_SPI_TARGET_SEL, 0); 81 } else { 82 altr_spi_writel(hw, ALTERA_SPI_TARGET_SEL, 83 BIT(spi_get_chipselect(spi, 0))); 84 hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK; 85 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr); 86 } 87 } 88 89 static void altera_spi_tx_word(struct altera_spi *hw) 90 { 91 unsigned int txd = 0; 92 93 if (hw->tx) { 94 switch (hw->bytes_per_word) { 95 case 1: 96 txd = hw->tx[hw->count]; 97 break; 98 case 2: 99 txd = (hw->tx[hw->count * 2] 100 | (hw->tx[hw->count * 2 + 1] << 8)); 101 break; 102 case 4: 103 txd = (hw->tx[hw->count * 4] 104 | (hw->tx[hw->count * 4 + 1] << 8) 105 | (hw->tx[hw->count * 4 + 2] << 16) 106 | (hw->tx[hw->count * 4 + 3] << 24)); 107 break; 108 109 } 110 } 111 112 altr_spi_writel(hw, ALTERA_SPI_TXDATA, txd); 113 } 114 115 static void altera_spi_rx_word(struct altera_spi *hw) 116 { 117 unsigned int rxd; 118 119 altr_spi_readl(hw, ALTERA_SPI_RXDATA, &rxd); 120 if (hw->rx) { 121 switch (hw->bytes_per_word) { 122 case 1: 123 hw->rx[hw->count] = rxd; 124 break; 125 case 2: 126 hw->rx[hw->count * 2] = rxd; 127 hw->rx[hw->count * 2 + 1] = rxd >> 8; 128 break; 129 case 4: 130 hw->rx[hw->count * 4] = rxd; 131 hw->rx[hw->count * 4 + 1] = rxd >> 8; 132 hw->rx[hw->count * 4 + 2] = rxd >> 16; 133 hw->rx[hw->count * 4 + 3] = rxd >> 24; 134 break; 135 136 } 137 } 138 139 hw->count++; 140 } 141 142 static int altera_spi_txrx(struct spi_controller *host, 143 struct spi_device *spi, struct spi_transfer *t) 144 { 145 struct altera_spi *hw = spi_controller_get_devdata(host); 146 u32 val; 147 148 hw->tx = t->tx_buf; 149 hw->rx = t->rx_buf; 150 hw->count = 0; 151 hw->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8); 152 hw->len = t->len / hw->bytes_per_word; 153 154 if (hw->irq >= 0) { 155 /* enable receive interrupt */ 156 hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK; 157 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr); 158 159 /* send the first byte */ 160 altera_spi_tx_word(hw); 161 162 return 1; 163 } 164 165 while (hw->count < hw->len) { 166 altera_spi_tx_word(hw); 167 168 for (;;) { 169 altr_spi_readl(hw, ALTERA_SPI_STATUS, &val); 170 if (val & ALTERA_SPI_STATUS_RRDY_MSK) 171 break; 172 173 cpu_relax(); 174 } 175 176 altera_spi_rx_word(hw); 177 } 178 spi_finalize_current_transfer(host); 179 180 return 0; 181 } 182 183 irqreturn_t altera_spi_irq(int irq, void *dev) 184 { 185 struct spi_controller *host = dev; 186 struct altera_spi *hw = spi_controller_get_devdata(host); 187 188 altera_spi_rx_word(hw); 189 190 if (hw->count < hw->len) { 191 altera_spi_tx_word(hw); 192 } else { 193 /* disable receive interrupt */ 194 hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK; 195 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr); 196 197 spi_finalize_current_transfer(host); 198 } 199 200 return IRQ_HANDLED; 201 } 202 EXPORT_SYMBOL_GPL(altera_spi_irq); 203 204 void altera_spi_init_host(struct spi_controller *host) 205 { 206 struct altera_spi *hw = spi_controller_get_devdata(host); 207 u32 val; 208 209 host->transfer_one = altera_spi_txrx; 210 host->set_cs = altera_spi_set_cs; 211 212 /* program defaults into the registers */ 213 hw->imr = 0; /* disable spi interrupts */ 214 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr); 215 altr_spi_writel(hw, ALTERA_SPI_STATUS, 0); /* clear status reg */ 216 altr_spi_readl(hw, ALTERA_SPI_STATUS, &val); 217 if (val & ALTERA_SPI_STATUS_RRDY_MSK) 218 altr_spi_readl(hw, ALTERA_SPI_RXDATA, &val); /* flush rxdata */ 219 } 220 EXPORT_SYMBOL_GPL(altera_spi_init_host); 221 222 MODULE_LICENSE("GPL"); 223