diff options
Diffstat (limited to 'drivers/spi/spi-mt7621.c')
| -rw-r--r-- | drivers/spi/spi-mt7621.c | 391 |
1 files changed, 391 insertions, 0 deletions
diff --git a/drivers/spi/spi-mt7621.c b/drivers/spi/spi-mt7621.c new file mode 100644 index 000000000..c4cc8e2f8 --- /dev/null +++ b/drivers/spi/spi-mt7621.c @@ -0,0 +1,391 @@ +// 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; + int pending_write; +}; + +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 clk *clk; + int ret; + + match = of_match_device(mt7621_spi_match, &pdev->dev); + if (!match) + return -EINVAL; + + base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(base)) + return PTR_ERR(base); + + clk = devm_clk_get_enabled(&pdev->dev, NULL); + if (IS_ERR(clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(clk), + "unable to get SYS clock\n"); + + master = devm_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->master = master; + rs->sys_freq = clk_get_rate(clk); + 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); +} + +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, +}; + +module_platform_driver(mt7621_spi_driver); + +MODULE_DESCRIPTION("MT7621 SPI driver"); +MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>"); +MODULE_LICENSE("GPL"); |