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Some SoCs in the mpc83xx family, e.g. mpc8309, have a dedicated spi chip select, SPISEL_BOOT, that is used by the boot code to boot from flash. This chip select will typically be used to select a SPI boot flash. The SPISEL_BOOT signal is controlled by a single bit in the SPI_CS register. Implement a gpio driver for the spi chip select register. This allows a spi driver capable of using gpios as chip select, to bind a chip select to SPISEL_BOOT. It may be a little odd to do this as a GPIO driver, since the signal is neither GP or I, but it is quite convenient to present it to the spi driver that way. The alternative it to teach mpc8xxx_spi to handle the SPISEL_BOOT signal itself (that is how it's done in the linux kernel, see commit 69b921acae8a) Signed-off-by: Klaus H. Sorensen <khso@prevas.dk> Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
23 lines
598 B
Plaintext
23 lines
598 B
Plaintext
MPC83xx SPISEL_BOOT gpio controller
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Provide access to MPC83xx SPISEL_BOOT signal as a gpio to allow it to be
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easily bound as a SPI controller chip select.
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The SPISEL_BOOT signal is always an output.
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Required properties:
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- compatible: must be "fsl,mpc83xx-spisel-boot" or "fsl,mpc8309-spisel-boot".
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- reg: must point to the SPI_CS register in the SoC register map.
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- ngpios: number of gpios provided by driver, normally 1.
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Example:
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spisel_boot: spisel_boot@14c {
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compatible = "fsl,mpc8309-spisel-boot";
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reg = <0x14c 0x04>;
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#gpio-cells = <2>;
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device_type = "gpio";
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ngpios = <1>;
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};
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