diff options
Diffstat (limited to 'drivers/spi/spi-mpfs.c')
| -rw-r--r-- | drivers/spi/spi-mpfs.c | 626 |
1 files changed, 626 insertions, 0 deletions
diff --git a/drivers/spi/spi-mpfs.c b/drivers/spi/spi-mpfs.c new file mode 100644 index 000000000000..9a14d1732a15 --- /dev/null +++ b/drivers/spi/spi-mpfs.c @@ -0,0 +1,626 @@ +// SPDX-License-Identifier: (GPL-2.0) +/* + * Microchip CoreSPI SPI controller driver + * + * Copyright (c) 2018-2022 Microchip Technology Inc. and its subsidiaries + * + * Author: Daire McNamara <daire.mcnamara@microchip.com> + * Author: Conor Dooley <conor.dooley@microchip.com> + * + */ + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/spi/spi.h> + +#define MAX_LEN (0xffff) +#define MAX_CS (1) +#define DEFAULT_FRAMESIZE (8) +#define FIFO_DEPTH (32) +#define CLK_GEN_MODE1_MAX (255) +#define CLK_GEN_MODE0_MAX (15) +#define CLK_GEN_MIN (0) +#define MODE_X_MASK_SHIFT (24) + +#define CONTROL_ENABLE BIT(0) +#define CONTROL_MASTER BIT(1) +#define CONTROL_RX_DATA_INT BIT(4) +#define CONTROL_TX_DATA_INT BIT(5) +#define CONTROL_RX_OVER_INT BIT(6) +#define CONTROL_TX_UNDER_INT BIT(7) +#define CONTROL_SPO BIT(24) +#define CONTROL_SPH BIT(25) +#define CONTROL_SPS BIT(26) +#define CONTROL_FRAMEURUN BIT(27) +#define CONTROL_CLKMODE BIT(28) +#define CONTROL_BIGFIFO BIT(29) +#define CONTROL_OENOFF BIT(30) +#define CONTROL_RESET BIT(31) + +#define CONTROL_MODE_MASK GENMASK(3, 2) +#define MOTOROLA_MODE (0) +#define CONTROL_FRAMECNT_MASK GENMASK(23, 8) +#define CONTROL_FRAMECNT_SHIFT (8) + +#define STATUS_ACTIVE BIT(14) +#define STATUS_SSEL BIT(13) +#define STATUS_FRAMESTART BIT(12) +#define STATUS_TXFIFO_EMPTY_NEXT_READ BIT(11) +#define STATUS_TXFIFO_EMPTY BIT(10) +#define STATUS_TXFIFO_FULL_NEXT_WRITE BIT(9) +#define STATUS_TXFIFO_FULL BIT(8) +#define STATUS_RXFIFO_EMPTY_NEXT_READ BIT(7) +#define STATUS_RXFIFO_EMPTY BIT(6) +#define STATUS_RXFIFO_FULL_NEXT_WRITE BIT(5) +#define STATUS_RXFIFO_FULL BIT(4) +#define STATUS_TX_UNDERRUN BIT(3) +#define STATUS_RX_OVERFLOW BIT(2) +#define STATUS_RXDAT_RXED BIT(1) +#define STATUS_TXDAT_SENT BIT(0) + +#define INT_TXDONE BIT(0) +#define INT_RXRDY BIT(1) +#define INT_RX_CHANNEL_OVERFLOW BIT(2) +#define INT_TX_CHANNEL_UNDERRUN BIT(3) + +#define INT_ENABLE_MASK (CONTROL_RX_OVER_INT | CONTROL_TX_UNDER_INT) + +#define REG_CONTROL (0x00) +#define REG_FRAME_SIZE (0x04) +#define FRAME_SIZE_MASK GENMASK(5, 0) +#define REG_STATUS (0x08) +#define REG_INT_CLEAR (0x0c) +#define REG_RX_DATA (0x10) +#define REG_TX_DATA (0x14) +#define REG_CLK_GEN (0x18) +#define REG_SLAVE_SELECT (0x1c) +#define SSEL_MASK GENMASK(7, 0) +#define SSEL_DIRECT BIT(8) +#define SSELOUT_SHIFT 9 +#define SSELOUT BIT(SSELOUT_SHIFT) +#define REG_MIS (0x20) +#define REG_RIS (0x24) +#define REG_CONTROL2 (0x28) +#define REG_COMMAND (0x2c) +#define COMMAND_CLRFRAMECNT BIT(4) +#define COMMAND_TXFIFORST BIT(3) +#define COMMAND_RXFIFORST BIT(2) +#define REG_PKTSIZE (0x30) +#define REG_CMD_SIZE (0x34) +#define REG_HWSTATUS (0x38) +#define REG_STAT8 (0x3c) +#define REG_CTRL2 (0x48) +#define REG_FRAMESUP (0x50) + +struct mpfs_spi { + void __iomem *regs; + struct clk *clk; + const u8 *tx_buf; + u8 *rx_buf; + u32 clk_gen; /* divider for spi output clock generated by the controller */ + u32 clk_mode; + u32 pending_slave_select; + int irq; + int tx_len; + int rx_len; + int n_bytes; +}; + +static inline u32 mpfs_spi_read(struct mpfs_spi *spi, unsigned int reg) +{ + return readl(spi->regs + reg); +} + +static inline void mpfs_spi_write(struct mpfs_spi *spi, unsigned int reg, u32 val) +{ + writel(val, spi->regs + reg); +} + +static inline void mpfs_spi_disable(struct mpfs_spi *spi) +{ + u32 control = mpfs_spi_read(spi, REG_CONTROL); + + control &= ~CONTROL_ENABLE; + + mpfs_spi_write(spi, REG_CONTROL, control); +} + +static inline void mpfs_spi_read_fifo(struct mpfs_spi *spi, int fifo_max) +{ + for (int i = 0; i < fifo_max; i++) { + u32 data; + + while (mpfs_spi_read(spi, REG_STATUS) & STATUS_RXFIFO_EMPTY) + ; + + data = mpfs_spi_read(spi, REG_RX_DATA); + + spi->rx_len -= spi->n_bytes; + + if (!spi->rx_buf) + continue; + + if (spi->n_bytes == 4) + *((u32 *)spi->rx_buf) = data; + else if (spi->n_bytes == 2) + *((u16 *)spi->rx_buf) = data; + else + *spi->rx_buf = data; + + spi->rx_buf += spi->n_bytes; + } +} + +static void mpfs_spi_enable_ints(struct mpfs_spi *spi) +{ + u32 control = mpfs_spi_read(spi, REG_CONTROL); + + control |= INT_ENABLE_MASK; + mpfs_spi_write(spi, REG_CONTROL, control); +} + +static void mpfs_spi_disable_ints(struct mpfs_spi *spi) +{ + u32 control = mpfs_spi_read(spi, REG_CONTROL); + + control &= ~INT_ENABLE_MASK; + mpfs_spi_write(spi, REG_CONTROL, control); +} + +static inline void mpfs_spi_set_xfer_size(struct mpfs_spi *spi, int len) +{ + u32 control; + u32 lenpart; + u32 frames = mpfs_spi_read(spi, REG_FRAMESUP); + + /* + * Writing to FRAMECNT in REG_CONTROL will reset the frame count, taking + * a shortcut requires an explicit clear. + */ + if (frames == len) { + mpfs_spi_write(spi, REG_COMMAND, COMMAND_CLRFRAMECNT); + return; + } + + /* + * The lower 16 bits of the frame count are stored in the control reg + * for legacy reasons, but the upper 16 written to a different register: + * FRAMESUP. While both the upper and lower bits can be *READ* from the + * FRAMESUP register, writing to the lower 16 bits is (supposedly) a NOP. + * + * The driver used to disable the controller while modifying the frame + * count, and mask off the lower 16 bits of len while writing to + * FRAMES_UP. When the driver was changed to disable the controller as + * infrequently as possible, it was discovered that the logic of + * lenpart = len & 0xffff_0000 + * write(REG_FRAMESUP, lenpart) + * would actually write zeros into the lower 16 bits on an mpfs250t-es, + * despite documentation stating these bits were read-only. + * Writing len unmasked into FRAMES_UP ensures those bits aren't zeroed + * on an mpfs250t-es and will be a NOP for the lower 16 bits on hardware + * that matches the documentation. + */ + lenpart = len & 0xffff; + control = mpfs_spi_read(spi, REG_CONTROL); + control &= ~CONTROL_FRAMECNT_MASK; + control |= lenpart << CONTROL_FRAMECNT_SHIFT; + mpfs_spi_write(spi, REG_CONTROL, control); + mpfs_spi_write(spi, REG_FRAMESUP, len); +} + +static inline void mpfs_spi_write_fifo(struct mpfs_spi *spi, int fifo_max) +{ + int i = 0; + + mpfs_spi_set_xfer_size(spi, fifo_max); + + while ((i < fifo_max) && !(mpfs_spi_read(spi, REG_STATUS) & STATUS_TXFIFO_FULL)) { + u32 word; + + if (spi->n_bytes == 4) + word = spi->tx_buf ? *((u32 *)spi->tx_buf) : 0xaa; + else if (spi->n_bytes == 2) + word = spi->tx_buf ? *((u16 *)spi->tx_buf) : 0xaa; + else + word = spi->tx_buf ? *spi->tx_buf : 0xaa; + + mpfs_spi_write(spi, REG_TX_DATA, word); + if (spi->tx_buf) + spi->tx_buf += spi->n_bytes; + i++; + } + + spi->tx_len -= i * spi->n_bytes; +} + +static inline void mpfs_spi_set_framesize(struct mpfs_spi *spi, int bt) +{ + u32 frame_size = mpfs_spi_read(spi, REG_FRAME_SIZE); + u32 control; + + if ((frame_size & FRAME_SIZE_MASK) == bt) + return; + + /* + * Disable the SPI controller. Writes to the frame size have + * no effect when the controller is enabled. + */ + control = mpfs_spi_read(spi, REG_CONTROL); + control &= ~CONTROL_ENABLE; + mpfs_spi_write(spi, REG_CONTROL, control); + + mpfs_spi_write(spi, REG_FRAME_SIZE, bt); + + control |= CONTROL_ENABLE; + mpfs_spi_write(spi, REG_CONTROL, control); +} + +static void mpfs_spi_set_cs(struct spi_device *spi, bool disable) +{ + u32 reg; + struct mpfs_spi *mspi = spi_controller_get_devdata(spi->controller); + + reg = mpfs_spi_read(mspi, REG_SLAVE_SELECT); + reg &= ~BIT(spi_get_chipselect(spi, 0)); + reg |= !disable << spi_get_chipselect(spi, 0); + mspi->pending_slave_select = reg; + + /* + * Only deassert chip select immediately. Writing to some registers + * requires the controller to be disabled, which results in the + * output pins being tristated and can cause the SCLK and MOSI lines + * to transition. Therefore asserting the chip select is deferred + * until just before writing to the TX FIFO, to ensure the device + * doesn't see any spurious clock transitions whilst CS is enabled. + */ + if (((spi->mode & SPI_CS_HIGH) == 0) == disable) + mpfs_spi_write(mspi, REG_SLAVE_SELECT, reg); +} + +static int mpfs_spi_setup(struct spi_device *spi) +{ + struct mpfs_spi *mspi = spi_controller_get_devdata(spi->controller); + u32 reg; + + if (spi_is_csgpiod(spi)) + return 0; + + /* + * Active high targets need to be specifically set to their inactive + * states during probe by adding them to the "control group" & thus + * driving their select line low. + */ + if (spi->mode & SPI_CS_HIGH) { + reg = mpfs_spi_read(mspi, REG_SLAVE_SELECT); + reg |= BIT(spi_get_chipselect(spi, 0)); + mspi->pending_slave_select = reg; + mpfs_spi_write(mspi, REG_SLAVE_SELECT, reg); + } + return 0; +} + +static void mpfs_spi_init(struct spi_controller *host, struct mpfs_spi *spi) +{ + unsigned long clk_hz; + u32 control = mpfs_spi_read(spi, REG_CONTROL); + + control &= ~CONTROL_ENABLE; + mpfs_spi_write(spi, REG_CONTROL, control); + + control |= CONTROL_MASTER; + control &= ~CONTROL_MODE_MASK; + control |= MOTOROLA_MODE; + + /* + * The controller must be configured so that it doesn't remove Chip + * Select until the entire message has been transferred, even if at + * some points TX FIFO becomes empty. + * + * BIGFIFO mode is also enabled, which sets the fifo depth to 32 frames + * for the 8 bit transfers that this driver uses. + */ + control |= CONTROL_SPS | CONTROL_BIGFIFO; + + mpfs_spi_write(spi, REG_CONTROL, control); + + mpfs_spi_set_framesize(spi, DEFAULT_FRAMESIZE); + + /* max. possible spi clock rate is the apb clock rate */ + clk_hz = clk_get_rate(spi->clk); + host->max_speed_hz = clk_hz; + + mpfs_spi_enable_ints(spi); + + /* + * It is required to enable direct mode, otherwise control over the chip + * select is relinquished to the hardware. SSELOUT is enabled too so we + * can deal with active high targets. + */ + spi->pending_slave_select = SSELOUT | SSEL_DIRECT; + mpfs_spi_write(spi, REG_SLAVE_SELECT, spi->pending_slave_select); + + control = mpfs_spi_read(spi, REG_CONTROL); + + control &= ~CONTROL_RESET; + control |= CONTROL_ENABLE; + + mpfs_spi_write(spi, REG_CONTROL, control); +} + +static inline void mpfs_spi_set_clk_gen(struct mpfs_spi *spi) +{ + u32 control; + + control = mpfs_spi_read(spi, REG_CONTROL); + if (spi->clk_mode) + control |= CONTROL_CLKMODE; + else + control &= ~CONTROL_CLKMODE; + + mpfs_spi_write(spi, REG_CLK_GEN, spi->clk_gen); + mpfs_spi_write(spi, REG_CONTROL, control); +} + +static inline void mpfs_spi_set_mode(struct mpfs_spi *spi, unsigned int mode) +{ + u32 mode_val; + u32 control = mpfs_spi_read(spi, REG_CONTROL); + + switch (mode & SPI_MODE_X_MASK) { + case SPI_MODE_0: + mode_val = 0; + break; + case SPI_MODE_1: + mode_val = CONTROL_SPH; + break; + case SPI_MODE_2: + mode_val = CONTROL_SPO; + break; + case SPI_MODE_3: + mode_val = CONTROL_SPH | CONTROL_SPO; + break; + } + + /* + * Disable the SPI controller. Writes to the frame protocol have + * no effect when the controller is enabled. + */ + + control &= ~CONTROL_ENABLE; + mpfs_spi_write(spi, REG_CONTROL, control); + + control &= ~(SPI_MODE_X_MASK << MODE_X_MASK_SHIFT); + control |= mode_val; + + mpfs_spi_write(spi, REG_CONTROL, control); + + control |= CONTROL_ENABLE; + mpfs_spi_write(spi, REG_CONTROL, control); +} + +static irqreturn_t mpfs_spi_interrupt(int irq, void *dev_id) +{ + struct spi_controller *host = dev_id; + struct mpfs_spi *spi = spi_controller_get_devdata(host); + u32 intfield = mpfs_spi_read(spi, REG_MIS) & 0xf; + bool finalise = false; + + /* Interrupt line may be shared and not for us at all */ + if (intfield == 0) + return IRQ_NONE; + + if (intfield & INT_RX_CHANNEL_OVERFLOW) { + mpfs_spi_write(spi, REG_INT_CLEAR, INT_RX_CHANNEL_OVERFLOW); + finalise = true; + dev_err(&host->dev, + "%s: RX OVERFLOW: rxlen: %d, txlen: %d\n", __func__, + spi->rx_len, spi->tx_len); + } + + if (intfield & INT_TX_CHANNEL_UNDERRUN) { + mpfs_spi_write(spi, REG_INT_CLEAR, INT_TX_CHANNEL_UNDERRUN); + finalise = true; + dev_err(&host->dev, + "%s: TX UNDERFLOW: rxlen: %d, txlen: %d\n", __func__, + spi->rx_len, spi->tx_len); + } + + if (finalise) + spi_finalize_current_transfer(host); + + return IRQ_HANDLED; +} + +static int mpfs_spi_calculate_clkgen(struct mpfs_spi *spi, + unsigned long target_hz) +{ + unsigned long clk_hz, spi_hz, clk_gen; + + clk_hz = clk_get_rate(spi->clk); + if (!clk_hz) + return -EINVAL; + spi_hz = min(target_hz, clk_hz); + + /* + * There are two possible clock modes for the controller generated + * clock's division ratio: + * CLK_MODE = 0: 1 / (2^(CLK_GEN + 1)) where CLK_GEN = 0 to 15. + * CLK_MODE = 1: 1 / (2 * CLK_GEN + 1) where CLK_GEN = 0 to 255. + * First try mode 1, fall back to 0 and if we have tried both modes and + * we /still/ can't get a good setting, we then throw the toys out of + * the pram and give up + * clk_gen is the register name for the clock divider on MPFS. + */ + clk_gen = DIV_ROUND_UP(clk_hz, 2 * spi_hz) - 1; + if (clk_gen > CLK_GEN_MODE1_MAX || clk_gen <= CLK_GEN_MIN) { + clk_gen = DIV_ROUND_UP(clk_hz, spi_hz); + clk_gen = fls(clk_gen) - 1; + + if (clk_gen > CLK_GEN_MODE0_MAX) + return -EINVAL; + + spi->clk_mode = 0; + } else { + spi->clk_mode = 1; + } + + spi->clk_gen = clk_gen; + return 0; +} + +static int mpfs_spi_transfer_one(struct spi_controller *host, + struct spi_device *spi_dev, + struct spi_transfer *xfer) +{ + struct mpfs_spi *spi = spi_controller_get_devdata(host); + int ret; + + ret = mpfs_spi_calculate_clkgen(spi, (unsigned long)xfer->speed_hz); + if (ret) { + dev_err(&host->dev, "failed to set clk_gen for target %u Hz\n", xfer->speed_hz); + return ret; + } + + mpfs_spi_set_clk_gen(spi); + + spi->tx_buf = xfer->tx_buf; + spi->rx_buf = xfer->rx_buf; + spi->tx_len = xfer->len; + spi->rx_len = xfer->len; + spi->n_bytes = roundup_pow_of_two(DIV_ROUND_UP(xfer->bits_per_word, BITS_PER_BYTE)); + + mpfs_spi_set_framesize(spi, xfer->bits_per_word); + + mpfs_spi_write(spi, REG_COMMAND, COMMAND_RXFIFORST | COMMAND_TXFIFORST); + + mpfs_spi_write(spi, REG_SLAVE_SELECT, spi->pending_slave_select); + + while (spi->tx_len) { + int fifo_max = DIV_ROUND_UP(min(spi->tx_len, FIFO_DEPTH), spi->n_bytes); + + mpfs_spi_write_fifo(spi, fifo_max); + mpfs_spi_read_fifo(spi, fifo_max); + } + + spi_finalize_current_transfer(host); + return 1; +} + +static int mpfs_spi_prepare_message(struct spi_controller *host, + struct spi_message *msg) +{ + struct spi_device *spi_dev = msg->spi; + struct mpfs_spi *spi = spi_controller_get_devdata(host); + + mpfs_spi_set_mode(spi, spi_dev->mode); + + return 0; +} + +static int mpfs_spi_probe(struct platform_device *pdev) +{ + struct spi_controller *host; + struct mpfs_spi *spi; + struct resource *res; + u32 num_cs; + int ret = 0; + + host = devm_spi_alloc_host(&pdev->dev, sizeof(*spi)); + if (!host) + return dev_err_probe(&pdev->dev, -ENOMEM, + "unable to allocate host for SPI controller\n"); + + platform_set_drvdata(pdev, host); + + if (of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs)) + num_cs = MAX_CS; + + host->num_chipselect = num_cs; + host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; + host->use_gpio_descriptors = true; + host->setup = mpfs_spi_setup; + host->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32); + host->transfer_one = mpfs_spi_transfer_one; + host->prepare_message = mpfs_spi_prepare_message; + host->set_cs = mpfs_spi_set_cs; + host->dev.of_node = pdev->dev.of_node; + + spi = spi_controller_get_devdata(host); + + spi->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &res); + if (IS_ERR(spi->regs)) + return PTR_ERR(spi->regs); + + spi->irq = platform_get_irq(pdev, 0); + if (spi->irq < 0) + return spi->irq; + + ret = devm_request_irq(&pdev->dev, spi->irq, mpfs_spi_interrupt, + IRQF_SHARED, dev_name(&pdev->dev), host); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "could not request irq\n"); + + spi->clk = devm_clk_get_enabled(&pdev->dev, NULL); + if (IS_ERR(spi->clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(spi->clk), + "could not get clk\n"); + + mpfs_spi_init(host, spi); + + ret = devm_spi_register_controller(&pdev->dev, host); + if (ret) { + mpfs_spi_disable(spi); + return dev_err_probe(&pdev->dev, ret, + "unable to register host for SPI controller\n"); + } + + dev_info(&pdev->dev, "Registered SPI controller %d\n", host->bus_num); + + return 0; +} + +static void mpfs_spi_remove(struct platform_device *pdev) +{ + struct spi_controller *host = platform_get_drvdata(pdev); + struct mpfs_spi *spi = spi_controller_get_devdata(host); + + mpfs_spi_disable_ints(spi); + mpfs_spi_disable(spi); +} + +#define MICROCHIP_SPI_PM_OPS (NULL) + +/* + * Platform driver data structure + */ + +#if defined(CONFIG_OF) +static const struct of_device_id mpfs_spi_dt_ids[] = { + { .compatible = "microchip,mpfs-spi" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, mpfs_spi_dt_ids); +#endif + +static struct platform_driver mpfs_spi_driver = { + .probe = mpfs_spi_probe, + .driver = { + .name = "microchip-spi", + .pm = MICROCHIP_SPI_PM_OPS, + .of_match_table = of_match_ptr(mpfs_spi_dt_ids), + }, + .remove = mpfs_spi_remove, +}; +module_platform_driver(mpfs_spi_driver); +MODULE_DESCRIPTION("Microchip coreSPI SPI controller driver"); +MODULE_AUTHOR("Daire McNamara <daire.mcnamara@microchip.com>"); +MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>"); +MODULE_LICENSE("GPL"); |
