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>

drivers/mtd/nand/Kconfig

@@ -519,6 +519,13 @@ config MTD_NAND_JZ4740
 	help
 		Enables support for NAND Flash on JZ4740 SoC based boards.
 
+config MTD_NAND_JZ4780
+	tristate "Support for NAND on JZ4780 SoC"
+	depends on MACH_JZ4780 && JZ4780_NEMC
+	help
+	  Enables support for NAND Flash connected to the NEMC on JZ4780 SoC
+	  based boards, using the BCH controller for hardware error correction.
+
 config MTD_NAND_FSMC
 	tristate "Support for NAND on ST Micros FSMC"
 	depends on PLAT_SPEAR || ARCH_NOMADIK || ARCH_U8500 || MACH_U300

drivers/mtd/nand/Makefile

@@ -49,6 +49,7 @@ obj-$(CONFIG_MTD_NAND_MPC5121_NFC)	+= mpc5121_nfc.o
 obj-$(CONFIG_MTD_NAND_VF610_NFC)	+= vf610_nfc.o
 obj-$(CONFIG_MTD_NAND_RICOH)		+= r852.o
 obj-$(CONFIG_MTD_NAND_JZ4740)		+= jz4740_nand.o
+obj-$(CONFIG_MTD_NAND_JZ4780)		+= jz4780_nand.o jz4780_bch.o
 obj-$(CONFIG_MTD_NAND_GPMI_NAND)	+= gpmi-nand/
 obj-$(CONFIG_MTD_NAND_XWAY)		+= xway_nand.o
 obj-$(CONFIG_MTD_NAND_BCM47XXNFLASH)	+= bcm47xxnflash/

drivers/mtd/nand/jz4780_bch.c

+/*
+ * JZ4780 BCH controller
+ *
+ * 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/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include "jz4780_bch.h"
+
+#define BCH_BHCR			0x0
+#define BCH_BHCCR			0x8
+#define BCH_BHCNT			0xc
+#define BCH_BHDR			0x10
+#define BCH_BHPAR0			0x14
+#define BCH_BHERR0			0x84
+#define BCH_BHINT			0x184
+#define BCH_BHINTES			0x188
+#define BCH_BHINTEC			0x18c
+#define BCH_BHINTE			0x190
+
+#define BCH_BHCR_BSEL_SHIFT		4
+#define BCH_BHCR_BSEL_MASK		(0x7f << BCH_BHCR_BSEL_SHIFT)
+#define BCH_BHCR_ENCE			BIT(2)
+#define BCH_BHCR_INIT			BIT(1)
+#define BCH_BHCR_BCHE			BIT(0)
+
+#define BCH_BHCNT_PARITYSIZE_SHIFT	16
+#define BCH_BHCNT_PARITYSIZE_MASK	(0x7f << BCH_BHCNT_PARITYSIZE_SHIFT)
+#define BCH_BHCNT_BLOCKSIZE_SHIFT	0
+#define BCH_BHCNT_BLOCKSIZE_MASK	(0x7ff << BCH_BHCNT_BLOCKSIZE_SHIFT)
+
+#define BCH_BHERR_MASK_SHIFT		16
+#define BCH_BHERR_MASK_MASK		(0xffff << BCH_BHERR_MASK_SHIFT)
+#define BCH_BHERR_INDEX_SHIFT		0
+#define BCH_BHERR_INDEX_MASK		(0x7ff << BCH_BHERR_INDEX_SHIFT)
+
+#define BCH_BHINT_ERRC_SHIFT		24
+#define BCH_BHINT_ERRC_MASK		(0x7f << BCH_BHINT_ERRC_SHIFT)
+#define BCH_BHINT_TERRC_SHIFT		16
+#define BCH_BHINT_TERRC_MASK		(0x7f << BCH_BHINT_TERRC_SHIFT)
+#define BCH_BHINT_DECF			BIT(3)
+#define BCH_BHINT_ENCF			BIT(2)
+#define BCH_BHINT_UNCOR			BIT(1)
+#define BCH_BHINT_ERR			BIT(0)
+
+#define BCH_CLK_RATE			(200 * 1000 * 1000)
+
+/* Timeout for BCH calculation/correction. */
+#define BCH_TIMEOUT_US			100000
+
+struct jz4780_bch {
+	struct device *dev;
+	void __iomem *base;
+	struct clk *clk;
+	struct mutex lock;
+};
+
+static void jz4780_bch_init(struct jz4780_bch *bch,
+			    struct jz4780_bch_params *params, bool encode)
+{
+	u32 reg;
+
+	/* Clear interrupt status. */
+	writel(readl(bch->base + BCH_BHINT), bch->base + BCH_BHINT);
+
+	/* Set up BCH count register. */
+	reg = params->size << BCH_BHCNT_BLOCKSIZE_SHIFT;
+	reg |= params->bytes << BCH_BHCNT_PARITYSIZE_SHIFT;
+	writel(reg, bch->base + BCH_BHCNT);
+
+	/* Initialise and enable BCH. */
+	reg = BCH_BHCR_BCHE | BCH_BHCR_INIT;
+	reg |= params->strength << BCH_BHCR_BSEL_SHIFT;
+	if (encode)
+		reg |= BCH_BHCR_ENCE;
+	writel(reg, bch->base + BCH_BHCR);
+}
+
+static void jz4780_bch_disable(struct jz4780_bch *bch)
+{
+	writel(readl(bch->base + BCH_BHINT), bch->base + BCH_BHINT);
+	writel(BCH_BHCR_BCHE, bch->base + BCH_BHCCR);
+}
+
+static void jz4780_bch_write_data(struct jz4780_bch *bch, const void *buf,
+				  size_t size)
+{
+	size_t size32 = size / sizeof(u32);
+	size_t size8 = size % sizeof(u32);
+	const u32 *src32;
+	const u8 *src8;
+
+	src32 = (const u32 *)buf;
+	while (size32--)
+		writel(*src32++, bch->base + BCH_BHDR);
+
+	src8 = (const u8 *)src32;
+	while (size8--)
+		writeb(*src8++, bch->base + BCH_BHDR);
+}
+
+static void jz4780_bch_read_parity(struct jz4780_bch *bch, void *buf,
+				   size_t size)
+{
+	size_t size32 = size / sizeof(u32);
+	size_t size8 = size % sizeof(u32);
+	u32 *dest32;
+	u8 *dest8;
+	u32 val, offset = 0;
+
+	dest32 = (u32 *)buf;
+	while (size32--) {
+		*dest32++ = readl(bch->base + BCH_BHPAR0 + offset);
+		offset += sizeof(u32);
+	}
+
+	dest8 = (u8 *)dest32;
+	val = readl(bch->base + BCH_BHPAR0 + offset);
+	switch (size8) {
+	case 3:
+		dest8[2] = (val >> 16) & 0xff;
+	case 2:
+		dest8[1] = (val >> 8) & 0xff;
+	case 1:
+		dest8[0] = val & 0xff;
+		break;
+	}
+}
+
+static bool jz4780_bch_wait_complete(struct jz4780_bch *bch, unsigned int irq,
+				     u32 *status)
+{
+	u32 reg;
+	int ret;
+
+	/*
+	 * While we could use interrupts here and sleep until the operation
+	 * completes, the controller works fairly quickly (usually a few
+	 * microseconds) and so the overhead of sleeping until we get an
+	 * interrupt quite noticeably decreases performance.
+	 */
+	ret = readl_poll_timeout(bch->base + BCH_BHINT, reg,
+				 (reg & irq) == irq, 0, BCH_TIMEOUT_US);
+	if (ret)
+		return false;
+
+	if (status)
+		*status = reg;
+
+	writel(reg, bch->base + BCH_BHINT);
+	return true;
+}
+
+/**
+ * jz4780_bch_calculate() - calculate ECC for a data buffer
+ * @bch: BCH device.
+ * @params: BCH parameters.
+ * @buf: input buffer with raw data.
+ * @ecc_code: output buffer with ECC.
+ *
+ * Return: 0 on success, -ETIMEDOUT if timed out while waiting for BCH
+ * controller.
+ */
+int jz4780_bch_calculate(struct jz4780_bch *bch, struct jz4780_bch_params *params,
+			 const u8 *buf, u8 *ecc_code)
+{
+	int ret = 0;
+
+	mutex_lock(&bch->lock);
+	jz4780_bch_init(bch, params, true);
+	jz4780_bch_write_data(bch, buf, params->size);
+
+	if (jz4780_bch_wait_complete(bch, BCH_BHINT_ENCF, NULL)) {
+		jz4780_bch_read_parity(bch, ecc_code, params->bytes);
+	} else {
+		dev_err(bch->dev, "timed out while calculating ECC\n");
+		ret = -ETIMEDOUT;
+	}
+
+	jz4780_bch_disable(bch);
+	mutex_unlock(&bch->lock);
+	return ret;
+}
+EXPORT_SYMBOL(jz4780_bch_calculate);
+
+/**
+ * jz4780_bch_correct() - detect and correct bit errors
+ * @bch: BCH device.
+ * @params: BCH parameters.
+ * @buf: raw data read from the chip.
+ * @ecc_code: ECC read from the chip.
+ *
+ * Given the raw data and the ECC read from the NAND device, detects and
+ * corrects errors in the data.
+ *
+ * Return: the number of bit errors corrected, or -1 if there are too many
+ * errors to correct or we timed out waiting for the controller.
+ */
+int jz4780_bch_correct(struct jz4780_bch *bch, struct jz4780_bch_params *params,
+		       u8 *buf, u8 *ecc_code)
+{
+	u32 reg, mask, index;
+	int i, ret, count;
+
+	mutex_lock(&bch->lock);
+
+	jz4780_bch_init(bch, params, false);
+	jz4780_bch_write_data(bch, buf, params->size);
+	jz4780_bch_write_data(bch, ecc_code, params->bytes);
+
+	if (!jz4780_bch_wait_complete(bch, BCH_BHINT_DECF, &reg)) {
+		dev_err(bch->dev, "timed out while correcting data\n");
+		ret = -1;
+		goto out;
+	}
+
+	if (reg & BCH_BHINT_UNCOR) {
+		dev_warn(bch->dev, "uncorrectable ECC error\n");
+		ret = -1;
+		goto out;
+	}
+
+	/* Correct any detected errors. */
+	if (reg & BCH_BHINT_ERR) {
+		count = (reg & BCH_BHINT_ERRC_MASK) >> BCH_BHINT_ERRC_SHIFT;
+		ret = (reg & BCH_BHINT_TERRC_MASK) >> BCH_BHINT_TERRC_SHIFT;
+
+		for (i = 0; i < count; i++) {
+			reg = readl(bch->base + BCH_BHERR0 + (i * 4));
+			mask = (reg & BCH_BHERR_MASK_MASK) >>
+						BCH_BHERR_MASK_SHIFT;
+			index = (reg & BCH_BHERR_INDEX_MASK) >>
+						BCH_BHERR_INDEX_SHIFT;
+			buf[(index * 2) + 0] ^= mask;
+			buf[(index * 2) + 1] ^= mask >> 8;
+		}
+	} else {
+		ret = 0;
+	}
+
+out:
+	jz4780_bch_disable(bch);
+	mutex_unlock(&bch->lock);
+	return ret;
+}
+EXPORT_SYMBOL(jz4780_bch_correct);
+
+/**
+ * jz4780_bch_get() - get the BCH controller device
+ * @np: BCH device tree node.
+ *
+ * Gets the BCH controller device from the specified device tree node. The
+ * device must be released with jz4780_bch_release() when it is no longer being
+ * used.
+ *
+ * Return: a pointer to jz4780_bch, errors are encoded into the pointer.
+ * PTR_ERR(-EPROBE_DEFER) if the device hasn't been initialised yet.
+ */
+static struct jz4780_bch *jz4780_bch_get(struct device_node *np)
+{
+	struct platform_device *pdev;
+	struct jz4780_bch *bch;
+
+	pdev = of_find_device_by_node(np);
+	if (!pdev || !platform_get_drvdata(pdev))
+		return ERR_PTR(-EPROBE_DEFER);
+
+	get_device(&pdev->dev);
+
+	bch = platform_get_drvdata(pdev);
+	clk_prepare_enable(bch->clk);
+
+	bch->dev = &pdev->dev;
+	return bch;
+}
+
+/**
+ * of_jz4780_bch_get() - get the BCH controller from a DT node
+ * @of_node: the node that contains a bch-controller property.
+ *
+ * Get the bch-controller property from the given device tree
+ * node and pass it to jz4780_bch_get to do the work.
+ *
+ * Return: a pointer to jz4780_bch, errors are encoded into the pointer.
+ * PTR_ERR(-EPROBE_DEFER) if the device hasn't been initialised yet.
+ */
+struct jz4780_bch *of_jz4780_bch_get(struct device_node *of_node)
+{
+	struct jz4780_bch *bch = NULL;
+	struct device_node *np;
+
+	np = of_parse_phandle(of_node, "ingenic,bch-controller", 0);
+
+	if (np) {
+		bch = jz4780_bch_get(np);
+		of_node_put(np);
+	}
+	return bch;
+}
+EXPORT_SYMBOL(of_jz4780_bch_get);
+
+/**
+ * jz4780_bch_release() - release the BCH controller device
+ * @bch: BCH device.
+ */
+void jz4780_bch_release(struct jz4780_bch *bch)
+{
+	clk_disable_unprepare(bch->clk);
+	put_device(bch->dev);
+}
+EXPORT_SYMBOL(jz4780_bch_release);
+
+static int jz4780_bch_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct jz4780_bch *bch;
+	struct resource *res;
+
+	bch = devm_kzalloc(dev, sizeof(*bch), GFP_KERNEL);
+	if (!bch)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	bch->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(bch->base))
+		return PTR_ERR(bch->base);
+
+	jz4780_bch_disable(bch);
+
+	bch->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(bch->clk)) {
+		dev_err(dev, "failed to get clock: %ld\n", PTR_ERR(bch->clk));
+		return PTR_ERR(bch->clk);
+	}
+
+	clk_set_rate(bch->clk, BCH_CLK_RATE);
+
+	mutex_init(&bch->lock);
+
+	bch->dev = dev;
+	platform_set_drvdata(pdev, bch);
+
+	return 0;
+}
+
+static const struct of_device_id jz4780_bch_dt_match[] = {
+	{ .compatible = "ingenic,jz4780-bch" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, jz4780_bch_dt_match);
+
+static struct platform_driver jz4780_bch_driver = {
+	.probe		= jz4780_bch_probe,
+	.driver	= {
+		.name	= "jz4780-bch",
+		.of_match_table = of_match_ptr(jz4780_bch_dt_match),
+	},
+};
+module_platform_driver(jz4780_bch_driver);
+
+MODULE_AUTHOR("Alex Smith <alex@alex-smith.me.uk>");
+MODULE_AUTHOR("Harvey Hunt <harvey.hunt@imgtec.com>");
+MODULE_DESCRIPTION("Ingenic JZ4780 BCH error correction driver");
+MODULE_LICENSE("GPL v2");

drivers/mtd/nand/jz4780_bch.h

+/*
+ * JZ4780 BCH controller
+ *
+ * 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.
+ */
+
+#ifndef __DRIVERS_MTD_NAND_JZ4780_BCH_H__
+#define __DRIVERS_MTD_NAND_JZ4780_BCH_H__
+
+#include <linux/types.h>
+
+struct device;
+struct device_node;
+struct jz4780_bch;
+
+/**
+ * struct jz4780_bch_params - BCH parameters
+ * @size: data bytes per ECC step.
+ * @bytes: ECC bytes per step.
+ * @strength: number of correctable bits per ECC step.
+ */
+struct jz4780_bch_params {
+	int size;
+	int bytes;
+	int strength;
+};
+
+int jz4780_bch_calculate(struct jz4780_bch *bch,
+				struct jz4780_bch_params *params,
+				const u8 *buf, u8 *ecc_code);
+int jz4780_bch_correct(struct jz4780_bch *bch,
+			      struct jz4780_bch_params *params, u8 *buf,
+			      u8 *ecc_code);
+
+void jz4780_bch_release(struct jz4780_bch *bch);
+struct jz4780_bch *of_jz4780_bch_get(struct device_node *np);
+
+#endif /* __DRIVERS_MTD_NAND_JZ4780_BCH_H__ */