drivers/spi/xilinx_spi.c

   1 /*
   2  * Xilinx SPI driver
   3  *
   4  * supports 8 bit SPI transfers only, with or w/o FIFO
   5  *
   6  * based on bfin_spi.c, by way of altera_spi.c
   7  * Copyright (c) 2005-2008 Analog Devices Inc.
   8  * Copyright (c) 2010 Thomas Chou <thomas@wytron.com.tw>
   9  * Copyright (c) 2010 Graeme Smecher <graeme.smecher@mail.mcgill.ca>
  10  * Copyright (c) 2012 Stephan Linz <linz@li-pro.net>
  11  *
  12  * Licensed under the GPL-2 or later.
  13  *
  14  * [0]: http://www.xilinx.com/support/documentation
  15  *
  16  * [S]: [0]/ip_documentation/xps_spi.pdf
  17  *      [0]/ip_documentation/axi_spi_ds742.pdf
  18  */
  19 #include <config.h>
  20 #include <common.h>
  21 #include <malloc.h>
  22 #include <spi.h>
  23
  24 #include "xilinx_spi.h"
  25
  26 #ifndef CONFIG_SYS_XILINX_SPI_LIST
  27 #define CONFIG_SYS_XILINX_SPI_LIST      { CONFIG_SYS_SPI_BASE }
  28 #endif
  29
  30 #ifndef CONFIG_XILINX_SPI_IDLE_VAL
  31 #define CONFIG_XILINX_SPI_IDLE_VAL      0xff
  32 #endif
  33
  34 #define XILSPI_SPICR_DFLT_ON            (SPICR_MANUAL_SS | \
  35                                          SPICR_MASTER_MODE | \
  36                                          SPICR_SPE)
  37
  38 #define XILSPI_SPICR_DFLT_OFF           (SPICR_MASTER_INHIBIT | \
  39                                          SPICR_MANUAL_SS)
  40
  41 #define XILSPI_MAX_XFER_BITS            8
  42
  43 static unsigned long xilinx_spi_base_list[] = CONFIG_SYS_XILINX_SPI_LIST;
  44
  45 __attribute__((weak))
  46 int spi_cs_is_valid(unsigned int bus, unsigned int cs)
  47 {
  48         return bus < ARRAY_SIZE(xilinx_spi_base_list) && cs < 32;
  49 }
  50
  51 __attribute__((weak))
  52 void spi_cs_activate(struct spi_slave *slave)
  53 {
  54         struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
  55
  56         writel(SPISSR_ACT(slave->cs), &xilspi->regs->spissr);
  57 }
  58
  59 __attribute__((weak))
  60 void spi_cs_deactivate(struct spi_slave *slave)
  61 {
  62         struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
  63
  64         writel(SPISSR_OFF, &xilspi->regs->spissr);
  65 }
  66
  67 void spi_init(void)
  68 {
  69         /* do nothing */
  70 }
  71
  72 void spi_set_speed(struct spi_slave *slave, uint hz)
  73 {
  74         /* xilinx spi core does not support programmable speed */
  75 }
  76
  77 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
  78                                   unsigned int max_hz, unsigned int mode)
  79 {
  80         struct xilinx_spi_slave *xilspi;
  81
  82         if (!spi_cs_is_valid(bus, cs)) {
  83                 printf("XILSPI error: %s: unsupported bus %d / cs %d\n",
  84                                 __func__, bus, cs);
  85                 return NULL;
  86         }
  87
  88         xilspi = malloc(sizeof(*xilspi));
  89         if (!xilspi) {
  90                 printf("XILSPI error: %s: malloc of SPI structure failed\n",
  91                                 __func__);
  92                 return NULL;
  93         }
  94         xilspi->slave.bus = bus;
  95         xilspi->slave.cs = cs;
  96         xilspi->regs = (struct xilinx_spi_reg *)xilinx_spi_base_list[bus];
  97         xilspi->freq = max_hz;
  98         xilspi->mode = mode;
  99         debug("%s: bus:%i cs:%i base:%p mode:%x max_hz:%d\n", __func__,
 100                 bus, cs, xilspi->regs, xilspi->mode, xilspi->freq);
 101
 102         return &xilspi->slave;
 103 }
 104
 105 void spi_free_slave(struct spi_slave *slave)
 106 {
 107         struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
 108
 109         free(xilspi);
 110 }
 111
 112 int spi_claim_bus(struct spi_slave *slave)
 113 {
 114         struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
 115         u32 spicr;
 116
 117         debug("%s: bus:%i cs:%i\n", __func__, slave->bus, slave->cs);
 118         writel(SPISSR_OFF, &xilspi->regs->spissr);
 119
 120         spicr = XILSPI_SPICR_DFLT_ON;
 121         if (xilspi->mode & SPI_LSB_FIRST)
 122                 spicr |= SPICR_LSB_FIRST;
 123         if (xilspi->mode & SPI_CPHA)
 124                 spicr |= SPICR_CPHA;
 125         if (xilspi->mode & SPI_CPOL)
 126                 spicr |= SPICR_CPOL;
 127         if (xilspi->mode & SPI_LOOP)
 128                 spicr |= SPICR_LOOP;
 129
 130         writel(spicr, &xilspi->regs->spicr);
 131         return 0;
 132 }
 133
 134 void spi_release_bus(struct spi_slave *slave)
 135 {
 136         struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
 137
 138         debug("%s: bus:%i cs:%i\n", __func__, slave->bus, slave->cs);
 139         writel(SPISSR_OFF, &xilspi->regs->spissr);
 140         writel(XILSPI_SPICR_DFLT_OFF, &xilspi->regs->spicr);
 141 }
 142
 143 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
 144              void *din, unsigned long flags)
 145 {
 146         struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
 147         /* assume spi core configured to do 8 bit transfers */
 148         unsigned int bytes = bitlen / XILSPI_MAX_XFER_BITS;
 149         const unsigned char *txp = dout;
 150         unsigned char *rxp = din;
 151         unsigned rxecount = 17; /* max. 16 elements in FIFO, leftover 1 */
 152
 153         debug("%s: bus:%i cs:%i bitlen:%i bytes:%i flags:%lx\n", __func__,
 154                 slave->bus, slave->cs, bitlen, bytes, flags);
 155         if (bitlen == 0)
 156                 goto done;
 157
 158         if (bitlen % XILSPI_MAX_XFER_BITS) {
 159                 printf("XILSPI warning: %s: Not a multiple of %d bits\n",
 160                                 __func__, XILSPI_MAX_XFER_BITS);
 161                 flags |= SPI_XFER_END;
 162                 goto done;
 163         }
 164
 165         /* empty read buffer */
 166         while (rxecount && !(readl(&xilspi->regs->spisr) & SPISR_RX_EMPTY)) {
 167                 readl(&xilspi->regs->spidrr);
 168                 rxecount--;
 169         }
 170
 171         if (!rxecount) {
 172                 printf("XILSPI error: %s: Rx buffer not empty\n", __func__);
 173                 return -1;
 174         }
 175
 176         if (flags & SPI_XFER_BEGIN)
 177                 spi_cs_activate(slave);
 178
 179         while (bytes--) {
 180                 unsigned timeout = /* at least 1usec or greater, leftover 1 */
 181                         xilspi->freq > XILSPI_MAX_XFER_BITS * 1000000 ? 2 :
 182                         (XILSPI_MAX_XFER_BITS * 1000000 / xilspi->freq) + 1;
 183
 184                 /* get Tx element from data out buffer and count up */
 185                 unsigned char d = txp ? *txp++ : CONFIG_XILINX_SPI_IDLE_VAL;
 186                 debug("%s: tx:%x ", __func__, d);
 187
 188                 /* write out and wait for processing (receive data) */
 189                 writel(d & SPIDTR_8BIT_MASK, &xilspi->regs->spidtr);
 190                 while (timeout && readl(&xilspi->regs->spisr)
 191                                                 & SPISR_RX_EMPTY) {
 192                         timeout--;
 193                         udelay(1);
 194                 }
 195
 196                 if (!timeout) {
 197                         printf("XILSPI error: %s: Xfer timeout\n", __func__);
 198                         return -1;
 199                 }
 200
 201                 /* read Rx element and push into data in buffer */
 202                 d = readl(&xilspi->regs->spidrr) & SPIDRR_8BIT_MASK;
 203                 if (rxp)
 204                         *rxp++ = d;
 205                 debug("rx:%x\n", d);
 206         }
 207
 208  done:
 209         if (flags & SPI_XFER_END)
 210                 spi_cs_deactivate(slave);
 211
 212         return 0;
 213 }