contrib/loaders/flash/stmqspi/stmqspi_read.S

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2
   3 /***************************************************************************
   4  *   Copyright (C) 2019 by Andreas Bolsch                                  *
   5  *   andreas.bolsch@mni.thm.de                                             *
   6  ***************************************************************************/
   7
   8         .text
   9         .syntax unified
  10         .cpu cortex-m0
  11         .thumb
  12         .thumb_func
  13
  14 /* Params:
  15  * r0 - total count (bytes), remaining bytes (out, 0 means successful)
  16  * r1 - flash page size
  17  * r2 - address offset into flash
  18  * r3 - QSPI io_base
  19  * r8 - fifo start
  20  * r9 - fifo end + 1
  21
  22  * Clobbered:
  23  * r4 - wp
  24  * r5 - address of QSPI_DR
  25  * r7 - tmp
  26  */
  27
  28 #include "../../../../src/flash/nor/stmqspi.h"
  29
  30         .macro  qspi_abort
  31         movs    r5, #(1<<SPI_ABORT)                     /* abort bit mask */
  32         ldr             r7, [r3, #QSPI_CR]                      /* get QSPI_CR register */
  33         orrs    r7, r7, r5                                      /* set abort bit */
  34         str             r7, [r3, #QSPI_CR]                      /* store new CR register */
  35         .endm
  36
  37         .macro  wait_busy
  38 0:
  39         ldr             r7, [r3, #QSPI_SR]                      /* load status */
  40         lsrs    r7, r7, #(SPI_BUSY+1)           /* shift BUSY into C */
  41         bcs             0b                                                      /* loop until BUSY cleared */
  42         movs    r7, #(1<<SPI_TCF)                       /* TCF bitmask */
  43         str             r7, [r3, #QSPI_FCR]                     /* clear TCF flag */
  44         .endm
  45
  46 start:
  47         subs    r0, r0, #1                                      /* decrement count for DLR */
  48         subs    r1, r1, #1                                      /* page size mask and for DLR */
  49         ldr             r4, wp                                          /* load wp */
  50 start_read:
  51         qspi_abort                                                      /* start in clean state */
  52         movs    r5, #QSPI_DR                            /* load QSPI_DR address offset */
  53         adds    r5, r5, r3                                      /* address of QSPI_DR */
  54         wait_busy
  55         mov             r7, r2                                          /* get current start address */
  56         orrs    r7, r7, r1                                      /* end of current page */
  57         subs    r7, r7, r2                                      /* count-1 to end of page */
  58         cmp             r7, r0                                          /* if this count <= remaining */
  59         bls             write_dlr                                       /* then read to end of page */
  60         mov             r7, r0                                          /* else read all remaining */
  61 write_dlr:
  62         str             r7, [r3, #QSPI_DLR]                     /* size-1 in DLR register */
  63         ldr             r7, ccr_page_read                       /* CCR for page read */
  64         str             r7, [r3, #QSPI_CCR]                     /* initiate transfer */
  65         str             r2, [r3, #QSPI_AR]                      /* store SPI start address */
  66         ldr             r7, [r3, #QSPI_SR]                      /* wait for command startup */
  67 read_loop:
  68         ldrb    r7, [r5]                                        /* read next byte from DR */
  69         strb    r7, [r4, #0]                            /* write next byte */
  70         adds    r4, r4, #1                                      /* increment internal wp */
  71         cmp             r4, r9                                          /* internal wp beyond end? */
  72         blo             wait_fifo                                       /* if no, then ok */
  73         mov             r4, r8                                          /* else wrap around */
  74 wait_fifo:
  75         ldr             r7, rp                                          /* get rp */
  76         cmp             r7, #0                                          /* if rp equals 0 */
  77         beq             exit                                            /* then abort */
  78         cmp             r4, r7                                          /* check if fifo full */
  79         beq             wait_fifo                                       /* wait until not full */
  80         adr             r7, wp                                          /* get address of wp */
  81         str             r4, [r7]                                        /* store updated wp */
  82         adds    r2, r2, #1                                      /* increment address */
  83         subs    r0, r0, #1                                      /* decrement (count-1) */
  84         bmi             exit                                            /* stop if no data left */
  85         tst             r2, r1                                          /* page end ? */
  86         bne             read_loop                                       /* if not, then next byte */
  87 page_end:
  88         bal             start_read                                      /* then next page */
  89
  90 exit:
  91         adds    r0, r0, #1                                      /* increment count due to the -1 */
  92         qspi_abort                                                      /* to idle state */
  93
  94         .align  2                                                       /* align to word, bkpt is 4 words */
  95         bkpt    #0                                                      /* before code end for exit_point */
  96         .align  2                                                       /* align to word */
  97
  98         .space  4                                                       /* not used */
  99         .space  4                                                       /* not used */
 100         .space  4                                                       /* not used */
 101         .space  4                                                       /* not used */
 102
 103         .space  4                                                       /* not used */
 104         .space  4                                                       /* not used */
 105         .space  4                                                       /* not used */
 106         .space  4                                                       /* not used */
 107
 108         .space  4                                                       /* not used */
 109 ccr_page_read:
 110         .space  4                                                       /* QSPI_CCR value for read command */
 111         .space  4                                                       /* not used */
 112         .space  4                                                       /* not used */
 113
 114         .equ wp, .                                                      /* wp, uint32_t */
 115         .equ rp, wp + 4                                         /* rp, uint32_t */
 116         .equ buffer, rp + 4                                     /* buffer follows right away */