spi: bcm53xx: driver for SPI controller on Broadcom bcma SoC

Broadcom 53xx ARM SoCs use bcma bus that contains various cores (AKA
devices). If board has a serial flash, it's connected over SPI and the
bcma bus includes a SPI controller. Example log from such a board:
bus0: Found chip with id 53010, rev 0x00 and package 0x02
(...)
bus0: Core 18 found: SPI flash controller (manuf 0x4BF, id 0x50A, rev 0x01, class 0x0)

This patch adds a bcma driver for SPI core, it registers SPI master
controller and "bcm53xxspiflash" SPI device.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 295 insertions, 0 deletions

diff --git a/drivers/spi/spi-bcm53xx.c b/drivers/spi/spi-bcm53xx.c
new file mode 100644
index 000000000000..48f13dfe7cf0
--- /dev/null
+++ b/drivers/spi/spi-bcm53xx.c
@@ -0,0 +1,295 @@
+#define pr_fmt(fmt)		KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/bcma/bcma.h>
+#include <linux/spi/spi.h>
+
+#include "spi-bcm53xx.h"
+
+#define BCM53XXSPI_MAX_SPI_BAUD	13500000	/* 216 MHz? */
+
+/* The longest observed required wait was 19 ms */
+#define BCM53XXSPI_SPE_TIMEOUT_MS	80
+
+struct bcm53xxspi {
+	struct bcma_device *core;
+	struct spi_master *master;
+
+	size_t read_offset;
+};
+
+static inline u32 bcm53xxspi_read(struct bcm53xxspi *b53spi, u16 offset)
+{
+	return bcma_read32(b53spi->core, offset);
+}
+
+static inline void bcm53xxspi_write(struct bcm53xxspi *b53spi, u16 offset,
+				    u32 value)
+{
+	bcma_write32(b53spi->core, offset, value);
+}
+
+static inline unsigned int bcm53xxspi_calc_timeout(size_t len)
+{
+	/* Do some magic calculation based on length and buad. Add 10% and 1. */
+	return (len * 9000 / BCM53XXSPI_MAX_SPI_BAUD * 110 / 100) + 1;
+}
+
+static int bcm53xxspi_wait(struct bcm53xxspi *b53spi, unsigned int timeout_ms)
+{
+	unsigned long deadline;
+	u32 tmp;
+
+	/* SPE bit has to be 0 before we read MSPI STATUS */
+	deadline = jiffies + BCM53XXSPI_SPE_TIMEOUT_MS * HZ / 1000;
+	do {
+		tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_SPCR2);
+		if (!(tmp & B53SPI_MSPI_SPCR2_SPE))
+			break;
+		udelay(5);
+	} while (!time_after_eq(jiffies, deadline));
+
+	if (tmp & B53SPI_MSPI_SPCR2_SPE)
+		goto spi_timeout;
+
+	/* Check status */
+	deadline = jiffies + timeout_ms * HZ / 1000;
+	do {
+		tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_MSPI_STATUS);
+		if (tmp & B53SPI_MSPI_MSPI_STATUS_SPIF) {
+			bcm53xxspi_write(b53spi, B53SPI_MSPI_MSPI_STATUS, 0);
+			return 0;
+		}
+
+		cpu_relax();
+		udelay(100);
+	} while (!time_after_eq(jiffies, deadline));
+
+spi_timeout:
+	bcm53xxspi_write(b53spi, B53SPI_MSPI_MSPI_STATUS, 0);
+
+	pr_err("Timeout waiting for SPI to be ready!\n");
+
+	return -EBUSY;
+}
+
+static void bcm53xxspi_buf_write(struct bcm53xxspi *b53spi, u8 *w_buf,
+				 size_t len, bool cont)
+{
+	u32 tmp;
+	int i;
+
+	for (i = 0; i < len; i++) {
+		/* Transmit Register File MSB */
+		bcm53xxspi_write(b53spi, B53SPI_MSPI_TXRAM + 4 * (i * 2),
+				 (unsigned int)w_buf[i]);
+	}
+
+	for (i = 0; i < len; i++) {
+		tmp = B53SPI_CDRAM_CONT | B53SPI_CDRAM_PCS_DISABLE_ALL |
+		      B53SPI_CDRAM_PCS_DSCK;
+		if (!cont && i == len - 1)
+			tmp &= ~B53SPI_CDRAM_CONT;
+		tmp &= ~0x1;
+		/* Command Register File */
+		bcm53xxspi_write(b53spi, B53SPI_MSPI_CDRAM + 4 * i, tmp);
+	}
+
+	/* Set queue pointers */
+	bcm53xxspi_write(b53spi, B53SPI_MSPI_NEWQP, 0);
+	bcm53xxspi_write(b53spi, B53SPI_MSPI_ENDQP, len - 1);
+
+	if (cont)
+		bcm53xxspi_write(b53spi, B53SPI_MSPI_WRITE_LOCK, 1);
+
+	/* Start SPI transfer */
+	tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_SPCR2);
+	tmp |= B53SPI_MSPI_SPCR2_SPE;
+	if (cont)
+		tmp |= B53SPI_MSPI_SPCR2_CONT_AFTER_CMD;
+	bcm53xxspi_write(b53spi, B53SPI_MSPI_SPCR2, tmp);
+
+	/* Wait for SPI to finish */
+	bcm53xxspi_wait(b53spi, bcm53xxspi_calc_timeout(len));
+
+	if (!cont)
+		bcm53xxspi_write(b53spi, B53SPI_MSPI_WRITE_LOCK, 0);
+
+	b53spi->read_offset = len;
+}
+
+static void bcm53xxspi_buf_read(struct bcm53xxspi *b53spi, u8 *r_buf,
+				size_t len, bool cont)
+{
+	u32 tmp;
+	int i;
+
+	for (i = 0; i < b53spi->read_offset + len; i++) {
+		tmp = B53SPI_CDRAM_CONT | B53SPI_CDRAM_PCS_DISABLE_ALL |
+		      B53SPI_CDRAM_PCS_DSCK;
+		if (!cont && i == b53spi->read_offset + len - 1)
+			tmp &= ~B53SPI_CDRAM_CONT;
+		tmp &= ~0x1;
+		/* Command Register File */
+		bcm53xxspi_write(b53spi, B53SPI_MSPI_CDRAM + 4 * i, tmp);
+	}
+
+	/* Set queue pointers */
+	bcm53xxspi_write(b53spi, B53SPI_MSPI_NEWQP, 0);
+	bcm53xxspi_write(b53spi, B53SPI_MSPI_ENDQP,
+			 b53spi->read_offset + len - 1);
+
+	if (cont)
+		bcm53xxspi_write(b53spi, B53SPI_MSPI_WRITE_LOCK, 1);
+
+	/* Start SPI transfer */
+	tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_SPCR2);
+	tmp |= B53SPI_MSPI_SPCR2_SPE;
+	if (cont)
+		tmp |= B53SPI_MSPI_SPCR2_CONT_AFTER_CMD;
+	bcm53xxspi_write(b53spi, B53SPI_MSPI_SPCR2, tmp);
+
+	/* Wait for SPI to finish */
+	bcm53xxspi_wait(b53spi, bcm53xxspi_calc_timeout(len));
+
+	if (!cont)
+		bcm53xxspi_write(b53spi, B53SPI_MSPI_WRITE_LOCK, 0);
+
+	for (i = 0; i < len; ++i) {
+		int offset = b53spi->read_offset + i;
+
+		/* Data stored in the transmit register file LSB */
+		r_buf[i] = (u8)bcm53xxspi_read(b53spi, B53SPI_MSPI_RXRAM + 4 * (1 + offset * 2));
+	}
+
+	b53spi->read_offset = 0;
+}
+
+static int bcm53xxspi_transfer_one(struct spi_master *master,
+				   struct spi_device *spi,
+				   struct spi_transfer *t)
+{
+	struct bcm53xxspi *b53spi = spi_master_get_devdata(master);
+	u8 *buf;
+	size_t left;
+
+	if (t->tx_buf) {
+		buf = (u8 *)t->tx_buf;
+		left = t->len;
+		while (left) {
+			size_t to_write = min_t(size_t, 16, left);
+			bool cont = left - to_write > 0;
+
+			bcm53xxspi_buf_write(b53spi, buf, to_write, cont);
+			left -= to_write;
+			buf += to_write;
+		}
+	}
+
+	if (t->rx_buf) {
+		buf = (u8 *)t->rx_buf;
+		left = t->len;
+		while (left) {
+			size_t to_read = min_t(size_t, 16 - b53spi->read_offset,
+					       left);
+			bool cont = left - to_read > 0;
+
+			bcm53xxspi_buf_read(b53spi, buf, to_read, cont);
+			left -= to_read;
+			buf += to_read;
+		}
+	}
+
+	return 0;
+}
+
+/**************************************************
+ * BCMA
+ **************************************************/
+
+struct spi_board_info bcm53xx_info = {
+	.modalias	= "bcm53xxspiflash",
+};
+
+static const struct bcma_device_id bcm53xxspi_bcma_tbl[] = {
+	BCMA_CORE(BCMA_MANUF_BCM, BCMA_CORE_NS_QSPI, BCMA_ANY_REV, BCMA_ANY_CLASS),
+	BCMA_CORETABLE_END
+};
+MODULE_DEVICE_TABLE(bcma, bcm53xxspi_bcma_tbl);
+
+static int bcm53xxspi_bcma_probe(struct bcma_device *core)
+{
+	struct bcm53xxspi *b53spi;
+	struct spi_master *master;
+	int err;
+
+	if (core->bus->drv_cc.core->id.rev != 42) {
+		pr_err("SPI on SoC with unsupported ChipCommon rev\n");
+		return -ENOTSUPP;
+	}
+
+	master = spi_alloc_master(&core->dev, sizeof(*b53spi));
+	if (!master)
+		return -ENOMEM;
+
+	b53spi = spi_master_get_devdata(master);
+	b53spi->master = master;
+	b53spi->core = core;
+
+	master->transfer_one = bcm53xxspi_transfer_one;
+
+	bcma_set_drvdata(core, b53spi);
+
+	err = devm_spi_register_master(&core->dev, master);
+	if (err) {
+		spi_master_put(master);
+		bcma_set_drvdata(core, NULL);
+		goto out;
+	}
+
+	/* Broadcom SoCs (at least with the CC rev 42) use SPI for flash only */
+	spi_new_device(master, &bcm53xx_info);
+
+out:
+	return err;
+}
+
+static void bcm53xxspi_bcma_remove(struct bcma_device *core)
+{
+	struct bcm53xxspi *b53spi = bcma_get_drvdata(core);
+
+	spi_unregister_master(b53spi->master);
+}
+
+static struct bcma_driver bcm53xxspi_bcma_driver = {
+	.name		= KBUILD_MODNAME,
+	.id_table	= bcm53xxspi_bcma_tbl,
+	.probe		= bcm53xxspi_bcma_probe,
+	.remove		= bcm53xxspi_bcma_remove,
+};
+
+/**************************************************
+ * Init & exit
+ **************************************************/
+
+static int __init bcm53xxspi_module_init(void)
+{
+	int err = 0;
+
+	err = bcma_driver_register(&bcm53xxspi_bcma_driver);
+	if (err)
+		pr_err("Failed to register bcma driver: %d\n", err);
+
+	return err;
+}
+
+static void __exit bcm53xxspi_module_exit(void)
+{
+	bcma_driver_unregister(&bcm53xxspi_bcma_driver);
+}
+
+module_init(bcm53xxspi_module_init);
+module_exit(bcm53xxspi_module_exit);