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path: root/drivers/spi/spi-mt7621.c
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Diffstat (limited to 'drivers/spi/spi-mt7621.c')
-rw-r--r--drivers/spi/spi-mt7621.c421
1 files changed, 421 insertions, 0 deletions
diff --git a/drivers/spi/spi-mt7621.c b/drivers/spi/spi-mt7621.c
new file mode 100644
index 000000000000..ae836114ee3d
--- /dev/null
+++ b/drivers/spi/spi-mt7621.c
@@ -0,0 +1,421 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// spi-mt7621.c -- MediaTek MT7621 SPI controller driver
+//
+// Copyright (C) 2011 Sergiy <piratfm@gmail.com>
+// Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
+// Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name>
+//
+// Some parts are based on spi-orion.c:
+// Author: Shadi Ammouri <shadi@marvell.com>
+// Copyright (C) 2007-2008 Marvell Ltd.
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+
+#define DRIVER_NAME "spi-mt7621"
+
+/* in usec */
+#define RALINK_SPI_WAIT_MAX_LOOP 2000
+
+/* SPISTAT register bit field */
+#define SPISTAT_BUSY BIT(0)
+
+#define MT7621_SPI_TRANS 0x00
+#define SPITRANS_BUSY BIT(16)
+
+#define MT7621_SPI_OPCODE 0x04
+#define MT7621_SPI_DATA0 0x08
+#define MT7621_SPI_DATA4 0x18
+#define SPI_CTL_TX_RX_CNT_MASK 0xff
+#define SPI_CTL_START BIT(8)
+
+#define MT7621_SPI_MASTER 0x28
+#define MASTER_MORE_BUFMODE BIT(2)
+#define MASTER_FULL_DUPLEX BIT(10)
+#define MASTER_RS_CLK_SEL GENMASK(27, 16)
+#define MASTER_RS_CLK_SEL_SHIFT 16
+#define MASTER_RS_SLAVE_SEL GENMASK(31, 29)
+
+#define MT7621_SPI_MOREBUF 0x2c
+#define MT7621_SPI_POLAR 0x38
+#define MT7621_SPI_SPACE 0x3c
+
+#define MT7621_CPHA BIT(5)
+#define MT7621_CPOL BIT(4)
+#define MT7621_LSB_FIRST BIT(3)
+
+struct mt7621_spi {
+ struct spi_controller *master;
+ void __iomem *base;
+ unsigned int sys_freq;
+ unsigned int speed;
+ struct clk *clk;
+ int pending_write;
+
+ struct mt7621_spi_ops *ops;
+};
+
+static inline struct mt7621_spi *spidev_to_mt7621_spi(struct spi_device *spi)
+{
+ return spi_controller_get_devdata(spi->master);
+}
+
+static inline u32 mt7621_spi_read(struct mt7621_spi *rs, u32 reg)
+{
+ return ioread32(rs->base + reg);
+}
+
+static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg, u32 val)
+{
+ iowrite32(val, rs->base + reg);
+}
+
+static void mt7621_spi_set_cs(struct spi_device *spi, int enable)
+{
+ struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+ int cs = spi->chip_select;
+ u32 polar = 0;
+ u32 master;
+
+ /*
+ * Select SPI device 7, enable "more buffer mode" and disable
+ * full-duplex (only half-duplex really works on this chip
+ * reliably)
+ */
+ master = mt7621_spi_read(rs, MT7621_SPI_MASTER);
+ master |= MASTER_RS_SLAVE_SEL | MASTER_MORE_BUFMODE;
+ master &= ~MASTER_FULL_DUPLEX;
+ mt7621_spi_write(rs, MT7621_SPI_MASTER, master);
+
+ rs->pending_write = 0;
+
+ if (enable)
+ polar = BIT(cs);
+ mt7621_spi_write(rs, MT7621_SPI_POLAR, polar);
+}
+
+static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed)
+{
+ struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+ u32 rate;
+ u32 reg;
+
+ dev_dbg(&spi->dev, "speed:%u\n", speed);
+
+ rate = DIV_ROUND_UP(rs->sys_freq, speed);
+ dev_dbg(&spi->dev, "rate-1:%u\n", rate);
+
+ if (rate > 4097)
+ return -EINVAL;
+
+ if (rate < 2)
+ rate = 2;
+
+ reg = mt7621_spi_read(rs, MT7621_SPI_MASTER);
+ reg &= ~MASTER_RS_CLK_SEL;
+ reg |= (rate - 2) << MASTER_RS_CLK_SEL_SHIFT;
+ rs->speed = speed;
+
+ reg &= ~MT7621_LSB_FIRST;
+ if (spi->mode & SPI_LSB_FIRST)
+ reg |= MT7621_LSB_FIRST;
+
+ /*
+ * This SPI controller seems to be tested on SPI flash only and some
+ * bits are swizzled under other SPI modes probably due to incorrect
+ * wiring inside the silicon. Only mode 0 works correctly.
+ */
+ reg &= ~(MT7621_CPHA | MT7621_CPOL);
+
+ mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);
+
+ return 0;
+}
+
+static inline int mt7621_spi_wait_till_ready(struct mt7621_spi *rs)
+{
+ int i;
+
+ for (i = 0; i < RALINK_SPI_WAIT_MAX_LOOP; i++) {
+ u32 status;
+
+ status = mt7621_spi_read(rs, MT7621_SPI_TRANS);
+ if ((status & SPITRANS_BUSY) == 0)
+ return 0;
+ cpu_relax();
+ udelay(1);
+ }
+
+ return -ETIMEDOUT;
+}
+
+static void mt7621_spi_read_half_duplex(struct mt7621_spi *rs,
+ int rx_len, u8 *buf)
+{
+ int tx_len;
+
+ /*
+ * Combine with any pending write, and perform one or more half-duplex
+ * transactions reading 'len' bytes. Data to be written is already in
+ * MT7621_SPI_DATA.
+ */
+ tx_len = rs->pending_write;
+ rs->pending_write = 0;
+
+ while (rx_len || tx_len) {
+ int i;
+ u32 val = (min(tx_len, 4) * 8) << 24;
+ int rx = min(rx_len, 32);
+
+ if (tx_len > 4)
+ val |= (tx_len - 4) * 8;
+ val |= (rx * 8) << 12;
+ mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);
+
+ tx_len = 0;
+
+ val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
+ val |= SPI_CTL_START;
+ mt7621_spi_write(rs, MT7621_SPI_TRANS, val);
+
+ mt7621_spi_wait_till_ready(rs);
+
+ for (i = 0; i < rx; i++) {
+ if ((i % 4) == 0)
+ val = mt7621_spi_read(rs, MT7621_SPI_DATA0 + i);
+ *buf++ = val & 0xff;
+ val >>= 8;
+ }
+
+ rx_len -= i;
+ }
+}
+
+static inline void mt7621_spi_flush(struct mt7621_spi *rs)
+{
+ mt7621_spi_read_half_duplex(rs, 0, NULL);
+}
+
+static void mt7621_spi_write_half_duplex(struct mt7621_spi *rs,
+ int tx_len, const u8 *buf)
+{
+ int len = rs->pending_write;
+ int val = 0;
+
+ if (len & 3) {
+ val = mt7621_spi_read(rs, MT7621_SPI_OPCODE + (len & ~3));
+ if (len < 4) {
+ val <<= (4 - len) * 8;
+ val = swab32(val);
+ }
+ }
+
+ while (tx_len > 0) {
+ if (len >= 36) {
+ rs->pending_write = len;
+ mt7621_spi_flush(rs);
+ len = 0;
+ }
+
+ val |= *buf++ << (8 * (len & 3));
+ len++;
+ if ((len & 3) == 0) {
+ if (len == 4)
+ /* The byte-order of the opcode is weird! */
+ val = swab32(val);
+ mt7621_spi_write(rs, MT7621_SPI_OPCODE + len - 4, val);
+ val = 0;
+ }
+ tx_len -= 1;
+ }
+
+ if (len & 3) {
+ if (len < 4) {
+ val = swab32(val);
+ val >>= (4 - len) * 8;
+ }
+ mt7621_spi_write(rs, MT7621_SPI_OPCODE + (len & ~3), val);
+ }
+
+ rs->pending_write = len;
+}
+
+static int mt7621_spi_transfer_one_message(struct spi_controller *master,
+ struct spi_message *m)
+{
+ struct mt7621_spi *rs = spi_controller_get_devdata(master);
+ struct spi_device *spi = m->spi;
+ unsigned int speed = spi->max_speed_hz;
+ struct spi_transfer *t = NULL;
+ int status = 0;
+
+ mt7621_spi_wait_till_ready(rs);
+
+ list_for_each_entry(t, &m->transfers, transfer_list)
+ if (t->speed_hz < speed)
+ speed = t->speed_hz;
+
+ if (mt7621_spi_prepare(spi, speed)) {
+ status = -EIO;
+ goto msg_done;
+ }
+
+ /* Assert CS */
+ mt7621_spi_set_cs(spi, 1);
+
+ m->actual_length = 0;
+ list_for_each_entry(t, &m->transfers, transfer_list) {
+ if ((t->rx_buf) && (t->tx_buf)) {
+ /*
+ * This controller will shift some extra data out
+ * of spi_opcode if (mosi_bit_cnt > 0) &&
+ * (cmd_bit_cnt == 0). So the claimed full-duplex
+ * support is broken since we have no way to read
+ * the MISO value during that bit.
+ */
+ status = -EIO;
+ goto msg_done;
+ } else if (t->rx_buf) {
+ mt7621_spi_read_half_duplex(rs, t->len, t->rx_buf);
+ } else if (t->tx_buf) {
+ mt7621_spi_write_half_duplex(rs, t->len, t->tx_buf);
+ }
+ m->actual_length += t->len;
+ }
+
+ /* Flush data and deassert CS */
+ mt7621_spi_flush(rs);
+ mt7621_spi_set_cs(spi, 0);
+
+msg_done:
+ m->status = status;
+ spi_finalize_current_message(master);
+
+ return 0;
+}
+
+static int mt7621_spi_setup(struct spi_device *spi)
+{
+ struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+
+ if ((spi->max_speed_hz == 0) ||
+ (spi->max_speed_hz > (rs->sys_freq / 2)))
+ spi->max_speed_hz = (rs->sys_freq / 2);
+
+ if (spi->max_speed_hz < (rs->sys_freq / 4097)) {
+ dev_err(&spi->dev, "setup: requested speed is too low %d Hz\n",
+ spi->max_speed_hz);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static const struct of_device_id mt7621_spi_match[] = {
+ { .compatible = "ralink,mt7621-spi" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, mt7621_spi_match);
+
+static int mt7621_spi_probe(struct platform_device *pdev)
+{
+ const struct of_device_id *match;
+ struct spi_controller *master;
+ struct mt7621_spi *rs;
+ void __iomem *base;
+ struct resource *r;
+ int status = 0;
+ struct clk *clk;
+ struct mt7621_spi_ops *ops;
+ int ret;
+
+ match = of_match_device(mt7621_spi_match, &pdev->dev);
+ if (!match)
+ return -EINVAL;
+ ops = (struct mt7621_spi_ops *)match->data;
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ base = devm_ioremap_resource(&pdev->dev, r);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(clk)) {
+ dev_err(&pdev->dev, "unable to get SYS clock, err=%d\n",
+ status);
+ return PTR_ERR(clk);
+ }
+
+ status = clk_prepare_enable(clk);
+ if (status)
+ return status;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(*rs));
+ if (!master) {
+ dev_info(&pdev->dev, "master allocation failed\n");
+ return -ENOMEM;
+ }
+
+ master->mode_bits = SPI_LSB_FIRST;
+ master->flags = SPI_CONTROLLER_HALF_DUPLEX;
+ master->setup = mt7621_spi_setup;
+ master->transfer_one_message = mt7621_spi_transfer_one_message;
+ master->bits_per_word_mask = SPI_BPW_MASK(8);
+ master->dev.of_node = pdev->dev.of_node;
+ master->num_chipselect = 2;
+
+ dev_set_drvdata(&pdev->dev, master);
+
+ rs = spi_controller_get_devdata(master);
+ rs->base = base;
+ rs->clk = clk;
+ rs->master = master;
+ rs->sys_freq = clk_get_rate(rs->clk);
+ rs->ops = ops;
+ rs->pending_write = 0;
+ dev_info(&pdev->dev, "sys_freq: %u\n", rs->sys_freq);
+
+ ret = device_reset(&pdev->dev);
+ if (ret) {
+ dev_err(&pdev->dev, "SPI reset failed!\n");
+ return ret;
+ }
+
+ return devm_spi_register_controller(&pdev->dev, master);
+}
+
+static int mt7621_spi_remove(struct platform_device *pdev)
+{
+ struct spi_controller *master;
+ struct mt7621_spi *rs;
+
+ master = dev_get_drvdata(&pdev->dev);
+ rs = spi_controller_get_devdata(master);
+
+ clk_disable_unprepare(rs->clk);
+
+ return 0;
+}
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+
+static struct platform_driver mt7621_spi_driver = {
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = mt7621_spi_match,
+ },
+ .probe = mt7621_spi_probe,
+ .remove = mt7621_spi_remove,
+};
+
+module_platform_driver(mt7621_spi_driver);
+
+MODULE_DESCRIPTION("MT7621 SPI driver");
+MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>");
+MODULE_LICENSE("GPL");
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