--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Microchip 48L640 64 Kb SPI Serial EERAM
+ *
+ * Copyright Heiko Schocher <hs@denx.de>
+ *
+ * datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/20006055B.pdf
+ *
+ * we set continuous mode but reading/writing more bytes than
+ * pagesize seems to bring chip into state where readden values
+ * are wrong ... no idea why.
+ *
+ */
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/sizes.h>
+#include <linux/spi/flash.h>
+#include <linux/spi/spi.h>
+#include <linux/of_device.h>
+
+struct mchp48_caps {
+ unsigned int size;
+ unsigned int page_size;
+};
+
+struct mchp48l640_flash {
+ struct spi_device *spi;
+ struct mutex lock;
+ struct mtd_info mtd;
+ const struct mchp48_caps *caps;
+};
+
+#define MCHP48L640_CMD_WREN 0x06
+#define MCHP48L640_CMD_WRDI 0x04
+#define MCHP48L640_CMD_WRITE 0x02
+#define MCHP48L640_CMD_READ 0x03
+#define MCHP48L640_CMD_WRSR 0x01
+#define MCHP48L640_CMD_RDSR 0x05
+
+#define MCHP48L640_STATUS_RDY 0x01
+#define MCHP48L640_STATUS_WEL 0x02
+#define MCHP48L640_STATUS_BP0 0x04
+#define MCHP48L640_STATUS_BP1 0x08
+#define MCHP48L640_STATUS_SWM 0x10
+#define MCHP48L640_STATUS_PRO 0x20
+#define MCHP48L640_STATUS_ASE 0x40
+
+#define MCHP48L640_TIMEOUT 100
+
+#define MAX_CMD_SIZE 0x10
+
+#define to_mchp48l640_flash(x) container_of(x, struct mchp48l640_flash, mtd)
+
+static int mchp48l640_mkcmd(struct mchp48l640_flash *flash, u8 cmd, loff_t addr, char *buf)
+{
+ buf[0] = cmd;
+ buf[1] = addr >> 8;
+ buf[2] = addr;
+
+ return 3;
+}
+
+static int mchp48l640_read_status(struct mchp48l640_flash *flash, int *status)
+{
+ unsigned char cmd[2];
+ int ret;
+
+ cmd[0] = MCHP48L640_CMD_RDSR;
+ cmd[1] = 0x00;
+ mutex_lock(&flash->lock);
+ ret = spi_write_then_read(flash->spi, &cmd[0], 1, &cmd[1], 1);
+ mutex_unlock(&flash->lock);
+ if (!ret)
+ *status = cmd[1];
+ dev_dbg(&flash->spi->dev, "read status ret: %d status: %x", ret, *status);
+
+ return ret;
+}
+
+static int mchp48l640_waitforbit(struct mchp48l640_flash *flash, int bit, bool set)
+{
+ int ret, status;
+ unsigned long deadline;
+
+ deadline = jiffies + msecs_to_jiffies(MCHP48L640_TIMEOUT);
+ do {
+ ret = mchp48l640_read_status(flash, &status);
+ dev_dbg(&flash->spi->dev, "read status ret: %d bit: %x %sset status: %x",
+ ret, bit, (set ? "" : "not"), status);
+ if (ret)
+ return ret;
+
+ if (set) {
+ if ((status & bit) == bit)
+ return 0;
+ } else {
+ if ((status & bit) == 0)
+ return 0;
+ }
+
+ usleep_range(1000, 2000);
+ } while (!time_after_eq(jiffies, deadline));
+
+ dev_err(&flash->spi->dev, "Timeout waiting for bit %x %s set in status register.",
+ bit, (set ? "" : "not"));
+ return -ETIMEDOUT;
+}
+
+static int mchp48l640_write_prepare(struct mchp48l640_flash *flash, bool enable)
+{
+ unsigned char cmd[2];
+ int ret;
+
+ if (enable)
+ cmd[0] = MCHP48L640_CMD_WREN;
+ else
+ cmd[0] = MCHP48L640_CMD_WRDI;
+
+ mutex_lock(&flash->lock);
+ ret = spi_write(flash->spi, cmd, 1);
+ mutex_unlock(&flash->lock);
+
+ if (ret)
+ dev_err(&flash->spi->dev, "write %sable failed ret: %d",
+ (enable ? "en" : "dis"), ret);
+
+ dev_dbg(&flash->spi->dev, "write %sable success ret: %d",
+ (enable ? "en" : "dis"), ret);
+ if (enable)
+ return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_WEL, true);
+
+ return ret;
+}
+
+static int mchp48l640_set_mode(struct mchp48l640_flash *flash)
+{
+ unsigned char cmd[2];
+ int ret;
+
+ ret = mchp48l640_write_prepare(flash, true);
+ if (ret)
+ return ret;
+
+ cmd[0] = MCHP48L640_CMD_WRSR;
+ cmd[1] = MCHP48L640_STATUS_PRO;
+
+ mutex_lock(&flash->lock);
+ ret = spi_write(flash->spi, cmd, 2);
+ mutex_unlock(&flash->lock);
+ if (ret)
+ dev_err(&flash->spi->dev, "Could not set continuous mode ret: %d", ret);
+
+ return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_PRO, true);
+}
+
+static int mchp48l640_wait_rdy(struct mchp48l640_flash *flash)
+{
+ return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_RDY, false);
+};
+
+static int mchp48l640_write_page(struct mtd_info *mtd, loff_t to, size_t len,
+ size_t *retlen, const unsigned char *buf)
+{
+ struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
+ unsigned char *cmd;
+ int ret;
+ int cmdlen;
+
+ cmd = kmalloc((3 + len), GFP_KERNEL | GFP_DMA);
+ if (!cmd)
+ return -ENOMEM;
+
+ ret = mchp48l640_wait_rdy(flash);
+ if (ret)
+ goto fail;
+
+ ret = mchp48l640_write_prepare(flash, true);
+ if (ret)
+ goto fail;
+
+ mutex_lock(&flash->lock);
+ cmdlen = mchp48l640_mkcmd(flash, MCHP48L640_CMD_WRITE, to, cmd);
+ memcpy(&cmd[cmdlen], buf, len);
+ ret = spi_write(flash->spi, cmd, cmdlen + len);
+ mutex_unlock(&flash->lock);
+ if (!ret)
+ *retlen += len;
+ else
+ goto fail;
+
+ ret = mchp48l640_waitforbit(flash, MCHP48L640_STATUS_WEL, false);
+ if (ret)
+ goto fail;
+
+ kfree(cmd);
+ return 0;
+fail:
+ kfree(cmd);
+ dev_err(&flash->spi->dev, "write fail with: %d", ret);
+ return ret;
+};
+
+static int mchp48l640_write(struct mtd_info *mtd, loff_t to, size_t len,
+ size_t *retlen, const unsigned char *buf)
+{
+ struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
+ int ret;
+ size_t wlen = 0;
+ loff_t woff = to;
+ size_t ws;
+ size_t page_sz = flash->caps->page_size;
+
+ /*
+ * we set PRO bit (page rollover), but writing length > page size
+ * does result in total chaos, so write in 32 byte chunks.
+ */
+ while (wlen < len) {
+ ws = min((len - wlen), page_sz);
+ ret = mchp48l640_write_page(mtd, woff, ws, retlen, &buf[wlen]);
+ if (ret)
+ return ret;
+ wlen += ws;
+ woff += ws;
+ }
+
+ return ret;
+}
+
+static int mchp48l640_read_page(struct mtd_info *mtd, loff_t from, size_t len,
+ size_t *retlen, unsigned char *buf)
+{
+ struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
+ unsigned char *cmd;
+ int ret;
+ int cmdlen;
+
+ cmd = kmalloc((3 + len), GFP_KERNEL | GFP_DMA);
+ if (!cmd)
+ return -ENOMEM;
+
+ ret = mchp48l640_wait_rdy(flash);
+ if (ret)
+ goto fail;
+
+ mutex_lock(&flash->lock);
+ cmdlen = mchp48l640_mkcmd(flash, MCHP48L640_CMD_READ, from, cmd);
+ ret = spi_write_then_read(flash->spi, cmd, cmdlen, buf, len);
+ mutex_unlock(&flash->lock);
+ if (!ret)
+ *retlen += len;
+
+ return ret;
+
+fail:
+ kfree(cmd);
+ dev_err(&flash->spi->dev, "read fail with: %d", ret);
+ return ret;
+}
+
+static int mchp48l640_read(struct mtd_info *mtd, loff_t from, size_t len,
+ size_t *retlen, unsigned char *buf)
+{
+ struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
+ int ret;
+ size_t wlen = 0;
+ loff_t woff = from;
+ size_t ws;
+ size_t page_sz = flash->caps->page_size;
+
+ /*
+ * we set PRO bit (page rollover), but if read length > page size
+ * does result in total chaos in result ...
+ */
+ while (wlen < len) {
+ ws = min((len - wlen), page_sz);
+ ret = mchp48l640_read_page(mtd, woff, ws, retlen, &buf[wlen]);
+ if (ret)
+ return ret;
+ wlen += ws;
+ woff += ws;
+ }
+
+ return ret;
+};
+
+static const struct mchp48_caps mchp48l640_caps = {
+ .size = SZ_8K,
+ .page_size = 32,
+};
+
+static int mchp48l640_probe(struct spi_device *spi)
+{
+ struct mchp48l640_flash *flash;
+ struct flash_platform_data *data;
+ int err;
+ int status;
+
+ flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
+ if (!flash)
+ return -ENOMEM;
+
+ flash->spi = spi;
+ mutex_init(&flash->lock);
+ spi_set_drvdata(spi, flash);
+
+ err = mchp48l640_read_status(flash, &status);
+ if (err)
+ return err;
+
+ err = mchp48l640_set_mode(flash);
+ if (err)
+ return err;
+
+ data = dev_get_platdata(&spi->dev);
+
+ flash->caps = of_device_get_match_data(&spi->dev);
+ if (!flash->caps)
+ flash->caps = &mchp48l640_caps;
+
+ mtd_set_of_node(&flash->mtd, spi->dev.of_node);
+ flash->mtd.dev.parent = &spi->dev;
+ flash->mtd.type = MTD_RAM;
+ flash->mtd.flags = MTD_CAP_RAM;
+ flash->mtd.writesize = flash->caps->page_size;
+ flash->mtd.size = flash->caps->size;
+ flash->mtd._read = mchp48l640_read;
+ flash->mtd._write = mchp48l640_write;
+
+ err = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
+ data ? data->nr_parts : 0);
+ if (err)
+ return err;
+
+ return 0;
+}
+
+static int mchp48l640_remove(struct spi_device *spi)
+{
+ struct mchp48l640_flash *flash = spi_get_drvdata(spi);
+
+ return mtd_device_unregister(&flash->mtd);
+}
+
+static const struct of_device_id mchp48l640_of_table[] = {
+ {
+ .compatible = "microchip,48l640",
+ .data = &mchp48l640_caps,
+ },
+ {}
+};
+MODULE_DEVICE_TABLE(of, mchp48l640_of_table);
+
+static struct spi_driver mchp48l640_driver = {
+ .driver = {
+ .name = "mchp48l640",
+ .of_match_table = of_match_ptr(mchp48l640_of_table),
+ },
+ .probe = mchp48l640_probe,
+ .remove = mchp48l640_remove,
+};
+
+module_spi_driver(mchp48l640_driver);
+
+MODULE_DESCRIPTION("MTD SPI driver for Microchip 48l640 EERAM chips");
+MODULE_AUTHOR("Heiko Schocher <hs@denx.de>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("spi:mchp48l640");
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