mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs

Add a driver for NAND devices connected to the NEMC on JZ4780 SoCs, as
well as the hardware BCH controller. DMA is not currently implemented.

While older 47xx SoCs also have a BCH controller, they are incompatible
with the one in the 4780 due to differing register/bit positions, which
would make implementing a common driver for them quite messy.

Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: linux-mtd@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Harvey Hunt <harvey.hunt@imgtec.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[Brian: fixed a few small mistakes]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 425 insertions, 0 deletions

diff --git a/drivers/mtd/nand/jz4780_nand.c b/drivers/mtd/nand/jz4780_nand.c
new file mode 100644
index 000000000000..17eb9f264187
--- /dev/null
+++ b/drivers/mtd/nand/jz4780_nand.c
@@ -0,0 +1,425 @@
+/*
+ * JZ4780 NAND driver
+ *
+ * Copyright (c) 2015 Imagination Technologies
+ * Author: Alex Smith <alex.smith@imgtec.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of_mtd.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/nand.h>
+#include <linux/mtd/partitions.h>
+
+#include <linux/jz4780-nemc.h>
+
+#include "jz4780_bch.h"
+
+#define DRV_NAME	"jz4780-nand"
+
+#define OFFSET_DATA	0x00000000
+#define OFFSET_CMD	0x00400000
+#define OFFSET_ADDR	0x00800000
+
+/* Command delay when there is no R/B pin. */
+#define RB_DELAY_US	100
+
+struct jz4780_nand_cs {
+	unsigned int bank;
+	void __iomem *base;
+};
+
+struct jz4780_nand_controller {
+	struct device *dev;
+	struct jz4780_bch *bch;
+	struct nand_hw_control controller;
+	unsigned int num_banks;
+	struct list_head chips;
+	int selected;
+	struct jz4780_nand_cs cs[];
+};
+
+struct jz4780_nand_chip {
+	struct nand_chip chip;
+	struct list_head chip_list;
+
+	struct nand_ecclayout ecclayout;
+
+	struct gpio_desc *busy_gpio;
+	struct gpio_desc *wp_gpio;
+	unsigned int reading: 1;
+};
+
+static inline struct jz4780_nand_chip *to_jz4780_nand_chip(struct mtd_info *mtd)
+{
+	return container_of(mtd_to_nand(mtd), struct jz4780_nand_chip, chip);
+}
+
+static inline struct jz4780_nand_controller *to_jz4780_nand_controller(struct nand_hw_control *ctrl)
+{
+	return container_of(ctrl, struct jz4780_nand_controller, controller);
+}
+
+static void jz4780_nand_select_chip(struct mtd_info *mtd, int chipnr)
+{
+	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
+	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
+	struct jz4780_nand_cs *cs;
+
+	/* Ensure the currently selected chip is deasserted. */
+	if (chipnr == -1 && nfc->selected >= 0) {
+		cs = &nfc->cs[nfc->selected];
+		jz4780_nemc_assert(nfc->dev, cs->bank, false);
+	}
+
+	nfc->selected = chipnr;
+}
+
+static void jz4780_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
+				 unsigned int ctrl)
+{
+	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
+	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
+	struct jz4780_nand_cs *cs;
+
+	if (WARN_ON(nfc->selected < 0))
+		return;
+
+	cs = &nfc->cs[nfc->selected];
+
+	jz4780_nemc_assert(nfc->dev, cs->bank, ctrl & NAND_NCE);
+
+	if (cmd == NAND_CMD_NONE)
+		return;
+
+	if (ctrl & NAND_ALE)
+		writeb(cmd, cs->base + OFFSET_ADDR);
+	else if (ctrl & NAND_CLE)
+		writeb(cmd, cs->base + OFFSET_CMD);
+}
+
+static int jz4780_nand_dev_ready(struct mtd_info *mtd)
+{
+	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
+
+	return !gpiod_get_value_cansleep(nand->busy_gpio);
+}
+
+static void jz4780_nand_ecc_hwctl(struct mtd_info *mtd, int mode)
+{
+	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
+
+	nand->reading = (mode == NAND_ECC_READ);
+}
+
+static int jz4780_nand_ecc_calculate(struct mtd_info *mtd, const u8 *dat,
+				     u8 *ecc_code)
+{
+	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
+	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
+	struct jz4780_bch_params params;
+
+	/*
+	 * Don't need to generate the ECC when reading, BCH does it for us as
+	 * part of decoding/correction.
+	 */
+	if (nand->reading)
+		return 0;
+
+	params.size = nand->chip.ecc.size;
+	params.bytes = nand->chip.ecc.bytes;
+	params.strength = nand->chip.ecc.strength;
+
+	return jz4780_bch_calculate(nfc->bch, &params, dat, ecc_code);
+}
+
+static int jz4780_nand_ecc_correct(struct mtd_info *mtd, u8 *dat,
+				   u8 *read_ecc, u8 *calc_ecc)
+{
+	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
+	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
+	struct jz4780_bch_params params;
+
+	params.size = nand->chip.ecc.size;
+	params.bytes = nand->chip.ecc.bytes;
+	params.strength = nand->chip.ecc.strength;
+
+	return jz4780_bch_correct(nfc->bch, &params, dat, read_ecc);
+}
+
+static int jz4780_nand_init_ecc(struct jz4780_nand_chip *nand, struct device *dev)
+{
+	struct nand_chip *chip = &nand->chip;
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(chip->controller);
+	struct nand_ecclayout *layout = &nand->ecclayout;
+	u32 start, i;
+
+	chip->ecc.bytes = fls((1 + 8) * chip->ecc.size)	*
+				(chip->ecc.strength / 8);
+
+	if (nfc->bch && chip->ecc.mode == NAND_ECC_HW) {
+		chip->ecc.hwctl = jz4780_nand_ecc_hwctl;
+		chip->ecc.calculate = jz4780_nand_ecc_calculate;
+		chip->ecc.correct = jz4780_nand_ecc_correct;
+	} else if (!nfc->bch && chip->ecc.mode == NAND_ECC_HW) {
+		dev_err(dev, "HW BCH selected, but BCH controller not found\n");
+		return -ENODEV;
+	}
+
+	if (chip->ecc.mode == NAND_ECC_HW_SYNDROME) {
+		dev_err(dev, "ECC HW syndrome not supported\n");
+		return -EINVAL;
+	}
+
+	if (chip->ecc.mode != NAND_ECC_NONE)
+		dev_info(dev, "using %s (strength %d, size %d, bytes %d)\n",
+			(nfc->bch) ? "hardware BCH" : "software ECC",
+			chip->ecc.strength, chip->ecc.size, chip->ecc.bytes);
+	else
+		dev_info(dev, "not using ECC\n");
+
+	/* The NAND core will generate the ECC layout. */
+	if (chip->ecc.mode == NAND_ECC_SOFT || chip->ecc.mode == NAND_ECC_SOFT_BCH)
+		return 0;
+
+	/* Generate ECC layout. ECC codes are right aligned in the OOB area. */
+	layout->eccbytes = mtd->writesize / chip->ecc.size * chip->ecc.bytes;
+
+	if (layout->eccbytes > mtd->oobsize - 2) {
+		dev_err(dev,
+			"invalid ECC config: required %d ECC bytes, but only %d are available",
+			layout->eccbytes, mtd->oobsize - 2);
+		return -EINVAL;
+	}
+
+	start = mtd->oobsize - layout->eccbytes;
+	for (i = 0; i < layout->eccbytes; i++)
+		layout->eccpos[i] = start + i;
+
+	layout->oobfree[0].offset = 2;
+	layout->oobfree[0].length = mtd->oobsize - layout->eccbytes - 2;
+
+	chip->ecc.layout = layout;
+	return 0;
+}
+
+static int jz4780_nand_init_chip(struct platform_device *pdev,
+				struct jz4780_nand_controller *nfc,
+				struct device_node *np,
+				unsigned int chipnr)
+{
+	struct device *dev = &pdev->dev;
+	struct jz4780_nand_chip *nand;
+	struct jz4780_nand_cs *cs;
+	struct resource *res;
+	struct nand_chip *chip;
+	struct mtd_info *mtd;
+	const __be32 *reg;
+	int ret = 0;
+
+	cs = &nfc->cs[chipnr];
+
+	reg = of_get_property(np, "reg", NULL);
+	if (!reg)
+		return -EINVAL;
+
+	cs->bank = be32_to_cpu(*reg);
+
+	jz4780_nemc_set_type(nfc->dev, cs->bank, JZ4780_NEMC_BANK_NAND);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, chipnr);
+	cs->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(cs->base))
+		return PTR_ERR(cs->base);
+
+	nand = devm_kzalloc(dev, sizeof(*nand), GFP_KERNEL);
+	if (!nand)
+		return -ENOMEM;
+
+	nand->busy_gpio = devm_gpiod_get_optional(dev, "rb", GPIOD_IN);
+
+	if (IS_ERR(nand->busy_gpio)) {
+		ret = PTR_ERR(nand->busy_gpio);
+		dev_err(dev, "failed to request busy GPIO: %d\n", ret);
+		return ret;
+	} else if (nand->busy_gpio) {
+		nand->chip.dev_ready = jz4780_nand_dev_ready;
+	}
+
+	nand->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_LOW);
+
+	if (IS_ERR(nand->wp_gpio)) {
+		ret = PTR_ERR(nand->wp_gpio);
+		dev_err(dev, "failed to request WP GPIO: %d\n", ret);
+		return ret;
+	}
+
+	chip = &nand->chip;
+	mtd = nand_to_mtd(chip);
+	mtd->priv = chip;
+	mtd->name = devm_kasprintf(dev, GFP_KERNEL, "%s.%d", dev_name(dev),
+				   cs->bank);
+	if (!mtd->name)
+		return -ENOMEM;
+	mtd->dev.parent = dev;
+
+	chip->IO_ADDR_R = cs->base + OFFSET_DATA;
+	chip->IO_ADDR_W = cs->base + OFFSET_DATA;
+	chip->chip_delay = RB_DELAY_US;
+	chip->options = NAND_NO_SUBPAGE_WRITE;
+	chip->select_chip = jz4780_nand_select_chip;
+	chip->cmd_ctrl = jz4780_nand_cmd_ctrl;
+	chip->ecc.mode = NAND_ECC_HW;
+	chip->controller = &nfc->controller;
+	nand_set_flash_node(chip, np);
+
+	ret = nand_scan_ident(mtd, 1, NULL);
+	if (ret)
+		return ret;
+
+	ret = jz4780_nand_init_ecc(nand, dev);
+	if (ret)
+		return ret;
+
+	ret = nand_scan_tail(mtd);
+	if (ret)
+		return ret;
+
+	ret = mtd_device_register(mtd, NULL, 0);
+	if (ret) {
+		nand_release(mtd);
+		return ret;
+	}
+
+	list_add_tail(&nand->chip_list, &nfc->chips);
+
+	return 0;
+}
+
+static void jz4780_nand_cleanup_chips(struct jz4780_nand_controller *nfc)
+{
+	struct jz4780_nand_chip *chip;
+
+	while (!list_empty(&nfc->chips)) {
+		chip = list_first_entry(&nfc->chips, struct jz4780_nand_chip, chip_list);
+		nand_release(nand_to_mtd(&chip->chip));
+		list_del(&chip->chip_list);
+	}
+}
+
+static int jz4780_nand_init_chips(struct jz4780_nand_controller *nfc,
+				  struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np;
+	int i = 0;
+	int ret;
+	int num_chips = of_get_child_count(dev->of_node);
+
+	if (num_chips > nfc->num_banks) {
+		dev_err(dev, "found %d chips but only %d banks\n", num_chips, nfc->num_banks);
+		return -EINVAL;
+	}
+
+	for_each_child_of_node(dev->of_node, np) {
+		ret = jz4780_nand_init_chip(pdev, nfc, np, i);
+		if (ret) {
+			jz4780_nand_cleanup_chips(nfc);
+			return ret;
+		}
+
+		i++;
+	}
+
+	return 0;
+}
+
+static int jz4780_nand_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	unsigned int num_banks;
+	struct jz4780_nand_controller *nfc;
+	int ret;
+
+	num_banks = jz4780_nemc_num_banks(dev);
+	if (num_banks == 0) {
+		dev_err(dev, "no banks found\n");
+		return -ENODEV;
+	}
+
+	nfc = devm_kzalloc(dev, sizeof(*nfc) + (sizeof(nfc->cs[0]) * num_banks), GFP_KERNEL);
+	if (!nfc)
+		return -ENOMEM;
+
+	/*
+	 * Check for BCH HW before we call nand_scan_ident, to prevent us from
+	 * having to call it again if the BCH driver returns -EPROBE_DEFER.
+	 */
+	nfc->bch = of_jz4780_bch_get(dev->of_node);
+	if (IS_ERR(nfc->bch))
+		return PTR_ERR(nfc->bch);
+
+	nfc->dev = dev;
+	nfc->num_banks = num_banks;
+
+	spin_lock_init(&nfc->controller.lock);
+	INIT_LIST_HEAD(&nfc->chips);
+	init_waitqueue_head(&nfc->controller.wq);
+
+	ret = jz4780_nand_init_chips(nfc, pdev);
+	if (ret) {
+		if (nfc->bch)
+			jz4780_bch_release(nfc->bch);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, nfc);
+	return 0;
+}
+
+static int jz4780_nand_remove(struct platform_device *pdev)
+{
+	struct jz4780_nand_controller *nfc = platform_get_drvdata(pdev);
+
+	if (nfc->bch)
+		jz4780_bch_release(nfc->bch);
+
+	jz4780_nand_cleanup_chips(nfc);
+
+	return 0;
+}
+
+static const struct of_device_id jz4780_nand_dt_match[] = {
+	{ .compatible = "ingenic,jz4780-nand" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, jz4780_nand_dt_match);
+
+static struct platform_driver jz4780_nand_driver = {
+	.probe		= jz4780_nand_probe,
+	.remove		= jz4780_nand_remove,
+	.driver	= {
+		.name	= DRV_NAME,
+		.of_match_table = of_match_ptr(jz4780_nand_dt_match),
+	},
+};
+module_platform_driver(jz4780_nand_driver);
+
+MODULE_AUTHOR("Alex Smith <alex@alex-smith.me.uk>");
+MODULE_AUTHOR("Harvey Hunt <harvey.hunt@imgtec.com>");
+MODULE_DESCRIPTION("Ingenic JZ4780 NAND driver");
+MODULE_LICENSE("GPL v2");