// 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; }; 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; int status = 0; 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(&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->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");