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Annotation of qemu/roms/ipxe/src/drivers/nvs/threewire.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (C) 2006 Michael Brown <[email protected]>.
        !             3:  *
        !             4:  * This program is free software; you can redistribute it and/or
        !             5:  * modify it under the terms of the GNU General Public License as
        !             6:  * published by the Free Software Foundation; either version 2 of the
        !             7:  * License, or any later version.
        !             8:  *
        !             9:  * This program is distributed in the hope that it will be useful, but
        !            10:  * WITHOUT ANY WARRANTY; without even the implied warranty of
        !            11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
        !            12:  * General Public License for more details.
        !            13:  *
        !            14:  * You should have received a copy of the GNU General Public License
        !            15:  * along with this program; if not, write to the Free Software
        !            16:  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            17:  */
        !            18: 
        !            19: FILE_LICENCE ( GPL2_OR_LATER );
        !            20: 
        !            21: #include <stddef.h>
        !            22: #include <string.h>
        !            23: #include <assert.h>
        !            24: #include <unistd.h>
        !            25: #include <ipxe/threewire.h>
        !            26: 
        !            27: /** @file
        !            28:  *
        !            29:  * Three-wire serial devices
        !            30:  *
        !            31:  */
        !            32: 
        !            33: /**
        !            34:  * Read data from three-wire device
        !            35:  *
        !            36:  * @v nvs              NVS device
        !            37:  * @v address          Address from which to read
        !            38:  * @v data             Data buffer
        !            39:  * @v len              Length of data buffer
        !            40:  * @ret rc             Return status code
        !            41:  */
        !            42: int threewire_read ( struct nvs_device *nvs, unsigned int address,
        !            43:                     void *data, size_t len ) {
        !            44:        struct spi_device *device = nvs_to_spi ( nvs );
        !            45:        struct spi_bus *bus = device->bus;
        !            46:        int rc;
        !            47: 
        !            48:        assert ( bus->mode == SPI_MODE_THREEWIRE );
        !            49: 
        !            50:        DBGC ( device, "3wire %p reading %zd bytes at %04x\n",
        !            51:               device, len, address );
        !            52: 
        !            53:        if ( ( rc = bus->rw ( bus, device, THREEWIRE_READ, address,
        !            54:                              NULL, data, len ) ) != 0 ) {
        !            55:                DBGC ( device, "3wire %p could not read: %s\n",
        !            56:                       device, strerror ( rc ) );
        !            57:                return rc;
        !            58:        }
        !            59: 
        !            60:        return 0;
        !            61: }
        !            62: 
        !            63: /**
        !            64:  * Write data to three-wire device
        !            65:  *
        !            66:  * @v nvs              NVS device
        !            67:  * @v address          Address from which to read
        !            68:  * @v data             Data buffer
        !            69:  * @v len              Length of data buffer
        !            70:  * @ret rc             Return status code
        !            71:  */
        !            72: int threewire_write ( struct nvs_device *nvs, unsigned int address,
        !            73:                      const void *data, size_t len ) {
        !            74:        struct spi_device *device = nvs_to_spi ( nvs );
        !            75:        struct spi_bus *bus = device->bus;
        !            76:        int rc;
        !            77: 
        !            78:        assert ( bus->mode == SPI_MODE_THREEWIRE );
        !            79: 
        !            80:        DBGC ( device, "3wire %p writing %zd bytes at %04x\n",
        !            81:               device, len, address );
        !            82: 
        !            83:        /* Enable device for writing */
        !            84:        if ( ( rc = bus->rw ( bus, device, THREEWIRE_EWEN,
        !            85:                              THREEWIRE_EWEN_ADDRESS, NULL, NULL, 0 ) ) != 0 ){
        !            86:                DBGC ( device, "3wire %p could not enable writing: %s\n",
        !            87:                       device, strerror ( rc ) );
        !            88:                return rc;
        !            89:        }
        !            90: 
        !            91:        /* Write data */
        !            92:        if ( ( rc = bus->rw ( bus, device, THREEWIRE_WRITE, address,
        !            93:                              data, NULL, len ) ) != 0 ) {
        !            94:                DBGC ( device, "3wire %p could not write: %s\n",
        !            95:                       device, strerror ( rc ) );
        !            96:                return rc;
        !            97:        }
        !            98: 
        !            99:        /* Our model of an SPI bus doesn't provide a mechanism for
        !           100:         * "assert CS, wait for MISO to become high, so just wait for
        !           101:         * long enough to ensure that the write has completed.
        !           102:         */
        !           103:        mdelay ( THREEWIRE_WRITE_MDELAY );
        !           104: 
        !           105:        return 0;
        !           106: }
        !           107: 
        !           108: /**
        !           109:  * Autodetect device address length
        !           110:  *
        !           111:  * @v device           SPI device
        !           112:  * @ret rc             Return status code
        !           113:  */
        !           114: int threewire_detect_address_len ( struct spi_device *device ) {
        !           115:        struct nvs_device *nvs = &device->nvs;
        !           116:        int rc;
        !           117: 
        !           118:        DBGC ( device, "3wire %p autodetecting address length\n", device );
        !           119: 
        !           120:        device->address_len = SPI_AUTODETECT_ADDRESS_LEN;
        !           121:        if ( ( rc = threewire_read ( nvs, 0, NULL,
        !           122:                                     ( 1 << nvs->word_len_log2 ) ) ) != 0 ) {
        !           123:                DBGC ( device, "3wire %p could not autodetect address "
        !           124:                       "length: %s\n", device, strerror ( rc ) );
        !           125:                return rc;
        !           126:        }
        !           127: 
        !           128:        DBGC ( device, "3wire %p autodetected address length %d\n",
        !           129:               device, device->address_len );
        !           130:        return 0;
        !           131: }

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