drivers/spi/ath79_spi.c

   1 /*
   2  * Copyright (C) 2015-2016 Wills Wang <wills.wang@live.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0+
   5  */
   6
   7 #include <common.h>
   8 #include <spi.h>
   9 #include <dm.h>
  10 #include <div64.h>
  11 #include <errno.h>
  12 #include <asm/io.h>
  13 #include <asm/addrspace.h>
  14 #include <asm/types.h>
  15 #include <dm/pinctrl.h>
  16 #include <mach/ar71xx_regs.h>
  17
  18 /* CLOCK_DIVIDER = 3 (SPI clock = 200 / 8 ~ 25 MHz) */
  19 #define ATH79_SPI_CLK_DIV(x)           (((x) >> 1) - 1)
  20 #define ATH79_SPI_RRW_DELAY_FACTOR     12000
  21 #define ATH79_SPI_MHZ                  (1000 * 1000)
  22
  23 struct ath79_spi_priv {
  24         void __iomem *regs;
  25         u32 rrw_delay;
  26 };
  27
  28 static void spi_cs_activate(struct udevice *dev)
  29 {
  30         struct udevice *bus = dev_get_parent(dev);
  31         struct ath79_spi_priv *priv = dev_get_priv(bus);
  32
  33         writel(AR71XX_SPI_FS_GPIO, priv->regs + AR71XX_SPI_REG_FS);
  34         writel(AR71XX_SPI_IOC_CS_ALL, priv->regs + AR71XX_SPI_REG_IOC);
  35 }
  36
  37 static void spi_cs_deactivate(struct udevice *dev)
  38 {
  39         struct udevice *bus = dev_get_parent(dev);
  40         struct ath79_spi_priv *priv = dev_get_priv(bus);
  41
  42         writel(AR71XX_SPI_IOC_CS_ALL, priv->regs + AR71XX_SPI_REG_IOC);
  43         writel(0, priv->regs + AR71XX_SPI_REG_FS);
  44 }
  45
  46 static int ath79_spi_claim_bus(struct udevice *dev)
  47 {
  48         return 0;
  49 }
  50
  51 static int ath79_spi_release_bus(struct udevice *dev)
  52 {
  53         return 0;
  54 }
  55
  56 static int ath79_spi_xfer(struct udevice *dev, unsigned int bitlen,
  57                 const void *dout, void *din, unsigned long flags)
  58 {
  59         struct udevice *bus = dev_get_parent(dev);
  60         struct ath79_spi_priv *priv = dev_get_priv(bus);
  61         struct dm_spi_slave_platdata *slave = dev_get_parent_platdata(dev);
  62         u8 *rx = din;
  63         const u8 *tx = dout;
  64         u8 curbyte, curbitlen, restbits;
  65         u32 bytes = bitlen / 8;
  66         u32 out, in;
  67         u64 tick;
  68
  69         if (flags & SPI_XFER_BEGIN)
  70                 spi_cs_activate(dev);
  71
  72         restbits = (bitlen % 8);
  73         if (restbits)
  74                 bytes++;
  75
  76         out = AR71XX_SPI_IOC_CS_ALL & ~(AR71XX_SPI_IOC_CS(slave->cs));
  77         while (bytes > 0) {
  78                 bytes--;
  79                 curbyte = 0;
  80                 if (tx)
  81                         curbyte = *tx++;
  82
  83                 if (restbits && !bytes) {
  84                         curbitlen = restbits;
  85                         curbyte <<= 8 - restbits;
  86                 } else {
  87                         curbitlen = 8;
  88                 }
  89
  90                 for (curbyte <<= (8 - curbitlen); curbitlen; curbitlen--) {
  91                         if (curbyte & 0x80)
  92                                 out |= AR71XX_SPI_IOC_DO;
  93                         else
  94                                 out &= ~(AR71XX_SPI_IOC_DO);
  95
  96                         writel(out, priv->regs + AR71XX_SPI_REG_IOC);
  97
  98                         /* delay for low level */
  99                         if (priv->rrw_delay) {
 100                                 tick = get_ticks() + priv->rrw_delay;
 101                                 while (get_ticks() < tick)
 102                                         /*NOP*/;
 103                         }
 104
 105                         writel(out | AR71XX_SPI_IOC_CLK,
 106                                priv->regs + AR71XX_SPI_REG_IOC);
 107
 108                         /* delay for high level */
 109                         if (priv->rrw_delay) {
 110                                 tick = get_ticks() + priv->rrw_delay;
 111                                 while (get_ticks() < tick)
 112                                         /*NOP*/;
 113                         }
 114
 115                         curbyte <<= 1;
 116                 }
 117
 118                 if (!bytes)
 119                         writel(out, priv->regs + AR71XX_SPI_REG_IOC);
 120
 121                 in = readl(priv->regs + AR71XX_SPI_REG_RDS);
 122                 if (rx) {
 123                         if (restbits && !bytes)
 124                                 *rx++ = (in << (8 - restbits));
 125                         else
 126                                 *rx++ = in;
 127                 }
 128         }
 129
 130         if (flags & SPI_XFER_END)
 131                 spi_cs_deactivate(dev);
 132
 133         return 0;
 134 }
 135
 136
 137 static int ath79_spi_set_speed(struct udevice *bus, uint speed)
 138 {
 139         struct ath79_spi_priv *priv = dev_get_priv(bus);
 140         u32 val, div = 0;
 141         u64 time;
 142
 143         if (speed)
 144                 div = get_bus_freq(0) / speed;
 145
 146         if (div > 63)
 147                 div = 63;
 148
 149         if (div < 5)
 150                 div = 5;
 151
 152         /* calculate delay */
 153         time = get_tbclk();
 154         do_div(time, speed / 2);
 155         val = get_bus_freq(0) / ATH79_SPI_MHZ;
 156         val = ATH79_SPI_RRW_DELAY_FACTOR / val;
 157         if (time > val)
 158                 priv->rrw_delay = time - val + 1;
 159         else
 160                 priv->rrw_delay = 0;
 161
 162         writel(AR71XX_SPI_FS_GPIO, priv->regs + AR71XX_SPI_REG_FS);
 163         clrsetbits_be32(priv->regs + AR71XX_SPI_REG_CTRL,
 164                         AR71XX_SPI_CTRL_DIV_MASK,
 165                         ATH79_SPI_CLK_DIV(div));
 166         writel(0, priv->regs + AR71XX_SPI_REG_FS);
 167         return 0;
 168 }
 169
 170 static int ath79_spi_set_mode(struct udevice *bus, uint mode)
 171 {
 172         return 0;
 173 }
 174
 175 static int ath79_spi_probe(struct udevice *bus)
 176 {
 177         struct ath79_spi_priv *priv = dev_get_priv(bus);
 178         fdt_addr_t addr;
 179
 180         addr = devfdt_get_addr(bus);
 181         if (addr == FDT_ADDR_T_NONE)
 182                 return -EINVAL;
 183
 184         priv->regs = map_physmem(addr,
 185                                  AR71XX_SPI_SIZE,
 186                                  MAP_NOCACHE);
 187
 188         /* Init SPI Hardware, disable remap, set clock */
 189         writel(AR71XX_SPI_FS_GPIO, priv->regs + AR71XX_SPI_REG_FS);
 190         writel(AR71XX_SPI_CTRL_RD | ATH79_SPI_CLK_DIV(8),
 191                priv->regs + AR71XX_SPI_REG_CTRL);
 192         writel(0, priv->regs + AR71XX_SPI_REG_FS);
 193
 194         return 0;
 195 }
 196
 197 static int ath79_cs_info(struct udevice *bus, uint cs,
 198                            struct spi_cs_info *info)
 199 {
 200         /* Always allow activity on CS 0/1/2 */
 201         if (cs >= 3)
 202                 return -ENODEV;
 203
 204         return 0;
 205 }
 206
 207 static const struct dm_spi_ops ath79_spi_ops = {
 208         .claim_bus  = ath79_spi_claim_bus,
 209         .release_bus    = ath79_spi_release_bus,
 210         .xfer       = ath79_spi_xfer,
 211         .set_speed  = ath79_spi_set_speed,
 212         .set_mode   = ath79_spi_set_mode,
 213         .cs_info    = ath79_cs_info,
 214 };
 215
 216 static const struct udevice_id ath79_spi_ids[] = {
 217         { .compatible = "qca,ar7100-spi" },
 218         {}
 219 };
 220
 221 U_BOOT_DRIVER(ath79_spi) = {
 222         .name   = "ath79_spi",
 223         .id = UCLASS_SPI,
 224         .of_match = ath79_spi_ids,
 225         .ops    = &ath79_spi_ops,
 226         .priv_auto_alloc_size = sizeof(struct ath79_spi_priv),
 227         .probe  = ath79_spi_probe,
 228 };