1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup raspberrypi_spi |
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5 | * |
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6 | * @brief Raspberry Pi specific SPI definitions. |
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7 | */ |
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8 | |
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9 | /* |
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10 | * Copyright (c) 2014-2015 Andre Marques <andre.lousa.marques at gmail.com> |
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11 | * |
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12 | * The license and distribution terms for this file may be |
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13 | * found in the file LICENSE in this distribution or at |
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14 | * http://www.rtems.org/license/LICENSE. |
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15 | */ |
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16 | |
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17 | #ifndef LIBBSP_ARM_RASPBERRYPI_SPI_H |
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18 | #define LIBBSP_ARM_RASPBERRYPI_SPI_H |
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19 | |
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20 | #include <rtems/libi2c.h> |
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21 | |
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22 | #ifdef __cplusplus |
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23 | extern "C" { |
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24 | #endif /* __cplusplus */ |
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25 | |
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26 | /** |
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27 | * @name SPI constants. |
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28 | * |
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29 | * @{ |
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30 | */ |
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31 | |
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32 | /** |
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33 | * @brief GPU processor core clock rate in Hz. |
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34 | * |
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35 | * Unless configured otherwise on a "config.txt" file present on the SD card |
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36 | * the GPU defaults to 250 MHz. Currently only 250 MHz is supported. |
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37 | */ |
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38 | |
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39 | /* TODO: It would be nice if this value could be probed at startup, probably |
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40 | * using the Mailbox interface since the usual way of setting this on |
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41 | * the hardware is through a "config.txt" text file on the SD card. |
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42 | * Having this setup on the configure.ac script would require changing |
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43 | * the same setting on two different places. */ |
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44 | #define GPU_CORE_CLOCK_RATE 250000000 |
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45 | |
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46 | /** @} */ |
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47 | |
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48 | /** |
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49 | * @name SPI directives. |
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50 | * |
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51 | * @{ |
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52 | */ |
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53 | |
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54 | /** |
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55 | * @brief Setups the Raspberry Pi SPI bus (located on the GPIO header) |
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56 | * on the "/dev/spi" device file, and registers the bus on the |
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57 | * libi2c API. |
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58 | * |
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59 | * @param[in] bidirectional_mode If TRUE sets the SPI bus to use 2-wire SPI, |
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60 | * where the MOSI data line doubles as the |
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61 | * slave out (SO) and slave in (SI) data lines. |
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62 | * If FALSE the bus defaults to the usual |
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63 | * 3-wire SPI, with 2 separate data lines |
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64 | * (MOSI and MISO). |
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65 | * |
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66 | * @retval Returns libi2c bus number. |
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67 | * @retval <0 Could not register the bus. See @see rtems_libi2c_register_bus(). |
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68 | */ |
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69 | extern int rpi_spi_init(bool bidirectional_mode); |
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70 | |
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71 | /** @} */ |
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72 | |
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73 | #ifdef __cplusplus |
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74 | } |
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75 | #endif /* __cplusplus */ |
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76 | |
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77 | #endif /* LIBBSP_ARM_RASPBERRYPI_SPI_H */ |
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