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Unverified Commit 69b921ac authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Mark Brown
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spi: spi-fsl-spi: support use of the SPISEL_BOOT signal on MPC8309 



The MPC8309 has a dedicated signal, SPISEL_BOOT, usually used as chip
select for the flash device from which the bootloader is loaded. It is
not an ordinary gpio, but is simply controlled via the SPI_CS register
in the system configuration.

To allow accessing such a spi slave, we need to teach
fsl_spi_cs_control() how to control the SPISEL_BOOT signal. To
distinguish the gpio-controlled slaves, continue to have those use
chip_select values of 0..ngpios-1, and use chip_select == ngpios for
the boot flash.

I'm not too happy with all the ifdeffery, but it seems to be necessary
for guarding the sysdev/fsl_soc.h and use of
get_immrbase() (spi-fsl-lib.c already contains similar ifdeffery).

Googling suggests that the MPC8306 is similar, with the SPI_CS
register at the same offset.

Signed-off-by: default avatarRasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 84d8df74

Documentation/devicetree/bindings/spi/fsl-spi.txt

+4 −0
Original line number Diff line number Diff line
@@ -18,6 +18,10 @@ Optional properties: 
- gpios : specifies the gpio pins to be used for chipselects.

  The gpios will be referred to as reg = <index> in the SPI child nodes.

  If unspecified, a single SPI device without a chip select can be used.

- fsl,spisel_boot : for the MPC8306 and MPC8309, specifies that the

  SPISEL_BOOT signal is used as chip select for a slave device. Use

  reg = <number of gpios> in the corresponding child node, i.e. 0 if

  the gpios property is not present.



Example:

	spi@4c0 {

drivers/spi/spi-fsl-lib.h

+2 −0
Original line number Diff line number Diff line
@@ -95,8 +95,10 @@ static inline u32 mpc8xxx_spi_read_reg(__be32 __iomem *reg) 


struct mpc8xxx_spi_probe_info {

	struct fsl_spi_platform_data pdata;

	int ngpios;

	int *gpios;

	bool *alow_flags;

	__be32 __iomem *immr_spi_cs;

};



extern u32 mpc8xxx_spi_tx_buf_u8(struct mpc8xxx_spi *mpc8xxx_spi);

drivers/spi/spi-fsl-spi.c

+35 −5
Original line number Diff line number Diff line
@@ -39,6 +39,14 @@ 
#include <linux/spi/spi_bitbang.h>

#include <linux/types.h>



#ifdef CONFIG_FSL_SOC

#include <sysdev/fsl_soc.h>

#endif



/* Specific to the MPC8306/MPC8309 */

#define IMMR_SPI_CS_OFFSET 0x14c

#define SPI_BOOT_SEL_BIT   0x80000000



#include "spi-fsl-lib.h"

#include "spi-fsl-cpm.h"

#include "spi-fsl-spi.h"
@@ -701,10 +709,17 @@ static void fsl_spi_cs_control(struct spi_device *spi, bool on) 
	struct fsl_spi_platform_data *pdata = dev_get_platdata(dev);

	struct mpc8xxx_spi_probe_info *pinfo = to_of_pinfo(pdata);

	u16 cs = spi->chip_select;



	if (cs < pinfo->ngpios) {

		int gpio = pinfo->gpios[cs];

		bool alow = pinfo->alow_flags[cs];



		gpio_set_value(gpio, on ^ alow);

	} else {

		if (WARN_ON_ONCE(cs > pinfo->ngpios || !pinfo->immr_spi_cs))

			return;

		iowrite32be(on ? SPI_BOOT_SEL_BIT : 0, pinfo->immr_spi_cs);

	}

}



static int of_fsl_spi_get_chipselects(struct device *dev)
@@ -712,12 +727,15 @@ static int of_fsl_spi_get_chipselects(struct device *dev) 
	struct device_node *np = dev->of_node;

	struct fsl_spi_platform_data *pdata = dev_get_platdata(dev);

	struct mpc8xxx_spi_probe_info *pinfo = to_of_pinfo(pdata);

	bool spisel_boot = IS_ENABLED(CONFIG_FSL_SOC) &&

		of_property_read_bool(np, "fsl,spisel_boot");

	int ngpios;

	int i = 0;

	int ret;



	ngpios = of_gpio_count(np);

	if (ngpios <= 0) {

	ngpios = max(ngpios, 0);

	if (ngpios == 0 && !spisel_boot) {

		/*

		 * SPI w/o chip-select line. One SPI device is still permitted

		 * though.
@@ -726,6 +744,7 @@ static int of_fsl_spi_get_chipselects(struct device *dev) 
		return 0;

	}



	pinfo->ngpios = ngpios;

	pinfo->gpios = kmalloc_array(ngpios, sizeof(*pinfo->gpios),

				     GFP_KERNEL);

	if (!pinfo->gpios)
@@ -769,7 +788,18 @@ static int of_fsl_spi_get_chipselects(struct device *dev) 
		}

	}



	pdata->max_chipselect = ngpios;

#if IS_ENABLED(CONFIG_FSL_SOC)

	if (spisel_boot) {

		pinfo->immr_spi_cs = ioremap(get_immrbase() + IMMR_SPI_CS_OFFSET, 4);

		if (!pinfo->immr_spi_cs) {

			ret = -ENOMEM;

			i = ngpios - 1;

			goto err_loop;

		}

	}

#endif



	pdata->max_chipselect = ngpios + spisel_boot;

	pdata->cs_control = fsl_spi_cs_control;



	return 0;