drivers/staging/fbtft/fbtft-io.c

   1 #include <linux/export.h>
   2 #include <linux/errno.h>
   3 #include <linux/gpio.h>
   4 #include <linux/spi/spi.h>
   5 #include "fbtft.h"
   6
   7 int fbtft_write_spi(struct fbtft_par *par, void *buf, size_t len)
   8 {
   9         struct spi_transfer t = {
  10                 .tx_buf = buf,
  11                 .len = len,
  12         };
  13         struct spi_message m;
  14
  15         fbtft_par_dbg_hex(DEBUG_WRITE, par, par->info->device, u8, buf, len,
  16                 "%s(len=%d): ", __func__, len);
  17
  18         if (!par->spi) {
  19                 dev_err(par->info->device,
  20                         "%s: par->spi is unexpectedly NULL\n", __func__);
  21                 return -1;
  22         }
  23
  24         spi_message_init(&m);
  25         if (par->txbuf.dma && buf == par->txbuf.buf) {
  26                 t.tx_dma = par->txbuf.dma;
  27                 m.is_dma_mapped = 1;
  28         }
  29         spi_message_add_tail(&t, &m);
  30         return spi_sync(par->spi, &m);
  31 }
  32 EXPORT_SYMBOL(fbtft_write_spi);
  33
  34 /**
  35  * fbtft_write_spi_emulate_9() - write SPI emulating 9-bit
  36  * @par: Driver data
  37  * @buf: Buffer to write
  38  * @len: Length of buffer (must be divisible by 8)
  39  *
  40  * When 9-bit SPI is not available, this function can be used to emulate that.
  41  * par->extra must hold a transformation buffer used for transfer.
  42  */
  43 int fbtft_write_spi_emulate_9(struct fbtft_par *par, void *buf, size_t len)
  44 {
  45         u16 *src = buf;
  46         u8 *dst = par->extra;
  47         size_t size = len / 2;
  48         size_t added = 0;
  49         int bits, i, j;
  50         u64 val, dc, tmp;
  51
  52         fbtft_par_dbg_hex(DEBUG_WRITE, par, par->info->device, u8, buf, len,
  53                 "%s(len=%d): ", __func__, len);
  54
  55         if (!par->extra) {
  56                 dev_err(par->info->device, "%s: error: par->extra is NULL\n",
  57                         __func__);
  58                 return -EINVAL;
  59         }
  60         if ((len % 8) != 0) {
  61                 dev_err(par->info->device,
  62                         "error: len=%zu must be divisible by 8\n", len);
  63                 return -EINVAL;
  64         }
  65
  66         for (i = 0; i < size; i += 8) {
  67                 tmp = 0;
  68                 bits = 63;
  69                 for (j = 0; j < 7; j++) {
  70                         dc = (*src & 0x0100) ? 1 : 0;
  71                         val = *src & 0x00FF;
  72                         tmp |= dc << bits;
  73                         bits -= 8;
  74                         tmp |= val << bits--;
  75                         src++;
  76                 }
  77                 tmp |= ((*src & 0x0100) ? 1 : 0);
  78                 *(u64 *)dst = cpu_to_be64(tmp);
  79                 dst += 8;
  80                 *dst++ = (u8)(*src++ & 0x00FF);
  81                 added++;
  82         }
  83
  84         return spi_write(par->spi, par->extra, size + added);
  85 }
  86 EXPORT_SYMBOL(fbtft_write_spi_emulate_9);
  87
  88 int fbtft_read_spi(struct fbtft_par *par, void *buf, size_t len)
  89 {
  90         int ret;
  91         u8 txbuf[32] = { 0, };
  92         struct spi_transfer     t = {
  93                         .speed_hz = 2000000,
  94                         .rx_buf         = buf,
  95                         .len            = len,
  96                 };
  97         struct spi_message      m;
  98
  99         if (!par->spi) {
 100                 dev_err(par->info->device,
 101                         "%s: par->spi is unexpectedly NULL\n", __func__);
 102                 return -ENODEV;
 103         }
 104
 105         if (par->startbyte) {
 106                 if (len > 32) {
 107                         dev_err(par->info->device,
 108                                 "len=%zu can't be larger than 32 when using 'startbyte'\n",
 109                                 len);
 110                         return -EINVAL;
 111                 }
 112                 txbuf[0] = par->startbyte | 0x3;
 113                 t.tx_buf = txbuf;
 114                 fbtft_par_dbg_hex(DEBUG_READ, par, par->info->device, u8,
 115                         txbuf, len, "%s(len=%d) txbuf => ", __func__, len);
 116         }
 117
 118         spi_message_init(&m);
 119         spi_message_add_tail(&t, &m);
 120         ret = spi_sync(par->spi, &m);
 121         fbtft_par_dbg_hex(DEBUG_READ, par, par->info->device, u8, buf, len,
 122                 "%s(len=%d) buf <= ", __func__, len);
 123
 124         return ret;
 125 }
 126 EXPORT_SYMBOL(fbtft_read_spi);
 127
 128 /*
 129  * Optimized use of gpiolib is twice as fast as no optimization
 130  * only one driver can use the optimized version at a time
 131  */
 132 int fbtft_write_gpio8_wr(struct fbtft_par *par, void *buf, size_t len)
 133 {
 134         u8 data;
 135         int i;
 136 #ifndef DO_NOT_OPTIMIZE_FBTFT_WRITE_GPIO
 137         static u8 prev_data;
 138 #endif
 139
 140         fbtft_par_dbg_hex(DEBUG_WRITE, par, par->info->device, u8, buf, len,
 141                 "%s(len=%d): ", __func__, len);
 142
 143         while (len--) {
 144                 data = *(u8 *) buf;
 145
 146                 /* Start writing by pulling down /WR */
 147                 gpio_set_value(par->gpio.wr, 0);
 148
 149                 /* Set data */
 150 #ifndef DO_NOT_OPTIMIZE_FBTFT_WRITE_GPIO
 151                 if (data == prev_data) {
 152                         gpio_set_value(par->gpio.wr, 0); /* used as delay */
 153                 } else {
 154                         for (i = 0; i < 8; i++) {
 155                                 if ((data & 1) != (prev_data & 1))
 156                                         gpio_set_value(par->gpio.db[i],
 157                                                                 data & 1);
 158                                 data >>= 1;
 159                                 prev_data >>= 1;
 160                         }
 161                 }
 162 #else
 163                 for (i = 0; i < 8; i++) {
 164                         gpio_set_value(par->gpio.db[i], data & 1);
 165                         data >>= 1;
 166                 }
 167 #endif
 168
 169                 /* Pullup /WR */
 170                 gpio_set_value(par->gpio.wr, 1);
 171
 172 #ifndef DO_NOT_OPTIMIZE_FBTFT_WRITE_GPIO
 173                 prev_data = *(u8 *) buf;
 174 #endif
 175                 buf++;
 176         }
 177
 178         return 0;
 179 }
 180 EXPORT_SYMBOL(fbtft_write_gpio8_wr);
 181
 182 int fbtft_write_gpio16_wr(struct fbtft_par *par, void *buf, size_t len)
 183 {
 184         u16 data;
 185         int i;
 186 #ifndef DO_NOT_OPTIMIZE_FBTFT_WRITE_GPIO
 187         static u16 prev_data;
 188 #endif
 189
 190         fbtft_par_dbg_hex(DEBUG_WRITE, par, par->info->device, u8, buf, len,
 191                 "%s(len=%d): ", __func__, len);
 192
 193         while (len) {
 194                 data = *(u16 *) buf;
 195
 196                 /* Start writing by pulling down /WR */
 197                 gpio_set_value(par->gpio.wr, 0);
 198
 199                 /* Set data */
 200 #ifndef DO_NOT_OPTIMIZE_FBTFT_WRITE_GPIO
 201                 if (data == prev_data) {
 202                         gpio_set_value(par->gpio.wr, 0); /* used as delay */
 203                 } else {
 204                         for (i = 0; i < 16; i++) {
 205                                 if ((data & 1) != (prev_data & 1))
 206                                         gpio_set_value(par->gpio.db[i],
 207                                                                 data & 1);
 208                                 data >>= 1;
 209                                 prev_data >>= 1;
 210                         }
 211                 }
 212 #else
 213                 for (i = 0; i < 16; i++) {
 214                         gpio_set_value(par->gpio.db[i], data & 1);
 215                         data >>= 1;
 216                 }
 217 #endif
 218
 219                 /* Pullup /WR */
 220                 gpio_set_value(par->gpio.wr, 1);
 221
 222 #ifndef DO_NOT_OPTIMIZE_FBTFT_WRITE_GPIO
 223                 prev_data = *(u16 *) buf;
 224 #endif
 225                 buf += 2;
 226                 len -= 2;
 227         }
 228
 229         return 0;
 230 }
 231 EXPORT_SYMBOL(fbtft_write_gpio16_wr);
 232
 233 int fbtft_write_gpio16_wr_latched(struct fbtft_par *par, void *buf, size_t len)
 234 {
 235         dev_err(par->info->device, "%s: function not implemented\n", __func__);
 236         return -1;
 237 }
 238 EXPORT_SYMBOL(fbtft_write_gpio16_wr_latched);