mtd: rawnand: brcmnand: Add platform data structure for BCMA

Update the BCMA's chipcommon nand flash driver to detect which
chip-select is used and pass that information via platform data to the
brcmnand driver. Make sure that the brcmnand platform data structure is
always at the beginning of the platform data of the "nflash" device
created by BCMA to allow brcmnand to safely de-reference it.

Signed-off-by: Florian Fainelli <[e-mail]>
Signed-off-by: Miquel Raynal <[e-mail]>
Link: https://lore.kernel.org/linux-mtd/[e-mail]

MAINTAINERS

···
 L:	[e-mail]
 S:	Maintained
 F:	drivers/mtd/nand/raw/brcmnand/
+F:	include/linux/platform_data/brcmnand.h
 
 BROADCOM STB PCIE DRIVER
 M:	Jim Quinlan <[e-mail]>

drivers/bcma/driver_chipcommon_nflash.c

···
 
 #include "bcma_private.h"
 
+#include <linux/bitops.h>
 #include <linux/platform_device.h>
+#include <linux/platform_data/brcmnand.h>
 #include <linux/bcma/bcma.h>
+
+/* Alternate NAND controller driver name in order to allow both bcm47xxnflash
+ * and bcma_brcmnand to be built into the same kernel image.
+ */
+static const char *bcma_nflash_alt_name = "bcma_brcmnand";
 
 struct platform_device bcma_nflash_dev = {
 	.name		= "bcma_nflash",
 	.num_resources	= 0,
 };
 
+static const char *probes[] = { "bcm47xxpart", NULL };
+
 /* Initialize NAND flash access */
 int bcma_nflash_init(struct bcma_drv_cc *cc)
 {
 	struct bcma_bus *bus = cc->core->bus;
+	u32 reg;
 
 	if (bus->chipinfo.id != BCMA_CHIP_ID_BCM4706 &&
 	    cc->core->id.rev != 38) {
···
 
 	cc->nflash.present = true;
 	if (cc->core->id.rev == 38 &&
-	    (cc->status & BCMA_CC_CHIPST_5357_NAND_BOOT))
+	    (cc->status & BCMA_CC_CHIPST_5357_NAND_BOOT)) {
 		cc->nflash.boot = true;
+		/* Determine the chip select that is being used */
+		reg = bcma_cc_read32(cc, BCMA_CC_NAND_CS_NAND_SELECT) & 0xff;
+		cc->nflash.brcmnand_info.chip_select = ffs(reg) - 1;
+		cc->nflash.brcmnand_info.part_probe_types = probes;
+		cc->nflash.brcmnand_info.ecc_stepsize = 512;
+		cc->nflash.brcmnand_info.ecc_strength = 1;
+		bcma_nflash_dev.name = bcma_nflash_alt_name;
+	}
 
 	/* Prepare platform device, but don't register it yet. It's too early,
 	 * malloc (required by device_private_init) is not available yet. */

include/linux/bcma/bcma_driver_chipcommon.h

···
 #define LINUX_BCMA_DRIVER_CC_H_
 
 #include <linux/platform_device.h>
+#include <linux/platform_data/brcmnand.h>
 #include <linux/gpio.h>
 
 /** ChipCommon core registers. **/
···
 
 #ifdef CONFIG_BCMA_NFLASH
 struct bcma_nflash {
+	/* Must be the fist member for the brcmnand driver to
+	 * de-reference that structure.
+	 */
+	struct brcmnand_platform_data brcmnand_info;
 	bool present;
 	bool boot;		/* This is the flash the SoC boots from */
 };

include/linux/platform_data/brcmnand.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef BRCMNAND_PLAT_DATA_H
+#define BRCMNAND_PLAT_DATA_H
+
+struct brcmnand_platform_data {
+	int	chip_select;
+	const char * const *part_probe_types;
+	unsigned int ecc_stepsize;
+	unsigned int ecc_strength;
+};
+
+#endif /* BRCMNAND_PLAT_DATA_H */