diff options
Diffstat (limited to 'drivers/spi/spi-rzv2m-csi.c')
| -rw-r--r-- | drivers/spi/spi-rzv2m-csi.c | 657 |
1 files changed, 657 insertions, 0 deletions
diff --git a/drivers/spi/spi-rzv2m-csi.c b/drivers/spi/spi-rzv2m-csi.c new file mode 100644 index 0000000000..d0f51b17aa --- /dev/null +++ b/drivers/spi/spi-rzv2m-csi.c @@ -0,0 +1,657 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Renesas RZ/V2M Clocked Serial Interface (CSI) driver + * + * Copyright (C) 2023 Renesas Electronics Corporation + */ + +#include <linux/bits.h> +#include <linux/clk.h> +#include <linux/count_zeros.h> +#include <linux/interrupt.h> +#include <linux/iopoll.h> +#include <linux/log2.h> +#include <linux/platform_device.h> +#include <linux/property.h> +#include <linux/reset.h> +#include <linux/spi/spi.h> +#include <linux/units.h> + +/* Registers */ +#define CSI_MODE 0x00 /* CSI mode control */ +#define CSI_CLKSEL 0x04 /* CSI clock select */ +#define CSI_CNT 0x08 /* CSI control */ +#define CSI_INT 0x0C /* CSI interrupt status */ +#define CSI_IFIFOL 0x10 /* CSI receive FIFO level display */ +#define CSI_OFIFOL 0x14 /* CSI transmit FIFO level display */ +#define CSI_IFIFO 0x18 /* CSI receive window */ +#define CSI_OFIFO 0x1C /* CSI transmit window */ +#define CSI_FIFOTRG 0x20 /* CSI FIFO trigger level */ + +/* CSI_MODE */ +#define CSI_MODE_CSIE BIT(7) +#define CSI_MODE_TRMD BIT(6) +#define CSI_MODE_CCL BIT(5) +#define CSI_MODE_DIR BIT(4) +#define CSI_MODE_CSOT BIT(0) + +#define CSI_MODE_SETUP 0x00000040 + +/* CSI_CLKSEL */ +#define CSI_CLKSEL_CKP BIT(17) +#define CSI_CLKSEL_DAP BIT(16) +#define CSI_CLKSEL_MODE (CSI_CLKSEL_CKP|CSI_CLKSEL_DAP) +#define CSI_CLKSEL_SLAVE BIT(15) +#define CSI_CLKSEL_CKS GENMASK(14, 1) + +/* CSI_CNT */ +#define CSI_CNT_CSIRST BIT(28) +#define CSI_CNT_R_TRGEN BIT(19) +#define CSI_CNT_UNDER_E BIT(13) +#define CSI_CNT_OVERF_E BIT(12) +#define CSI_CNT_TREND_E BIT(9) +#define CSI_CNT_CSIEND_E BIT(8) +#define CSI_CNT_T_TRGR_E BIT(4) +#define CSI_CNT_R_TRGR_E BIT(0) + +/* CSI_INT */ +#define CSI_INT_UNDER BIT(13) +#define CSI_INT_OVERF BIT(12) +#define CSI_INT_TREND BIT(9) +#define CSI_INT_CSIEND BIT(8) +#define CSI_INT_T_TRGR BIT(4) +#define CSI_INT_R_TRGR BIT(0) + +/* CSI_FIFOTRG */ +#define CSI_FIFOTRG_R_TRG GENMASK(2, 0) + +#define CSI_FIFO_SIZE_BYTES 32U +#define CSI_FIFO_HALF_SIZE 16U +#define CSI_EN_DIS_TIMEOUT_US 100 +/* + * Clock "csiclk" gets divided by 2 * CSI_CLKSEL_CKS in order to generate the + * serial clock (output from master), with CSI_CLKSEL_CKS ranging from 0x1 (that + * means "csiclk" is divided by 2) to 0x3FFF ("csiclk" is divided by 32766). + */ +#define CSI_CKS_MAX GENMASK(13, 0) + +#define UNDERRUN_ERROR BIT(0) +#define OVERFLOW_ERROR BIT(1) +#define TX_TIMEOUT_ERROR BIT(2) +#define RX_TIMEOUT_ERROR BIT(3) + +#define CSI_MAX_SPI_SCKO (8 * HZ_PER_MHZ) + +struct rzv2m_csi_priv { + void __iomem *base; + struct clk *csiclk; + struct clk *pclk; + struct device *dev; + struct spi_controller *controller; + const void *txbuf; + void *rxbuf; + unsigned int buffer_len; + unsigned int bytes_sent; + unsigned int bytes_received; + unsigned int bytes_to_transfer; + unsigned int words_to_transfer; + unsigned int bytes_per_word; + wait_queue_head_t wait; + u32 errors; + u32 status; +}; + +static void rzv2m_csi_reg_write_bit(const struct rzv2m_csi_priv *csi, + int reg_offs, int bit_mask, u32 value) +{ + int nr_zeros; + u32 tmp; + + nr_zeros = count_trailing_zeros(bit_mask); + value <<= nr_zeros; + + tmp = (readl(csi->base + reg_offs) & ~bit_mask) | value; + writel(tmp, csi->base + reg_offs); +} + +static int rzv2m_csi_sw_reset(struct rzv2m_csi_priv *csi, int assert) +{ + u32 reg; + + rzv2m_csi_reg_write_bit(csi, CSI_CNT, CSI_CNT_CSIRST, assert); + + if (!assert) + return 0; + + return readl_poll_timeout(csi->base + CSI_MODE, reg, + !(reg & CSI_MODE_CSOT), 0, + CSI_EN_DIS_TIMEOUT_US); +} + +static int rzv2m_csi_start_stop_operation(const struct rzv2m_csi_priv *csi, + int enable, bool wait) +{ + u32 reg; + + rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_CSIE, enable); + + if (enable || !wait) + return 0; + + return readl_poll_timeout(csi->base + CSI_MODE, reg, + !(reg & CSI_MODE_CSOT), 0, + CSI_EN_DIS_TIMEOUT_US); +} + +static int rzv2m_csi_fill_txfifo(struct rzv2m_csi_priv *csi) +{ + unsigned int i; + + if (readl(csi->base + CSI_OFIFOL)) + return -EIO; + + if (csi->bytes_per_word == 2) { + const u16 *buf = csi->txbuf; + + for (i = 0; i < csi->words_to_transfer; i++) + writel(buf[i], csi->base + CSI_OFIFO); + } else { + const u8 *buf = csi->txbuf; + + for (i = 0; i < csi->words_to_transfer; i++) + writel(buf[i], csi->base + CSI_OFIFO); + } + + csi->txbuf += csi->bytes_to_transfer; + csi->bytes_sent += csi->bytes_to_transfer; + + return 0; +} + +static int rzv2m_csi_read_rxfifo(struct rzv2m_csi_priv *csi) +{ + unsigned int i; + + if (readl(csi->base + CSI_IFIFOL) != csi->bytes_to_transfer) + return -EIO; + + if (csi->bytes_per_word == 2) { + u16 *buf = csi->rxbuf; + + for (i = 0; i < csi->words_to_transfer; i++) + buf[i] = (u16)readl(csi->base + CSI_IFIFO); + } else { + u8 *buf = csi->rxbuf; + + for (i = 0; i < csi->words_to_transfer; i++) + buf[i] = (u8)readl(csi->base + CSI_IFIFO); + } + + csi->rxbuf += csi->bytes_to_transfer; + csi->bytes_received += csi->bytes_to_transfer; + + return 0; +} + +static inline void rzv2m_csi_calc_current_transfer(struct rzv2m_csi_priv *csi) +{ + unsigned int bytes_transferred = max(csi->bytes_received, csi->bytes_sent); + unsigned int bytes_remaining = csi->buffer_len - bytes_transferred; + unsigned int to_transfer; + + if (csi->txbuf) + /* + * Leaving a little bit of headroom in the FIFOs makes it very + * hard to raise an overflow error (which is only possible + * when IP transmits and receives at the same time). + */ + to_transfer = min(CSI_FIFO_HALF_SIZE, bytes_remaining); + else + to_transfer = min(CSI_FIFO_SIZE_BYTES, bytes_remaining); + + if (csi->bytes_per_word == 2) + to_transfer >>= 1; + + /* + * We can only choose a trigger level from a predefined set of values. + * This will pick a value that is the greatest possible integer that's + * less than or equal to the number of bytes we need to transfer. + * This may result in multiple smaller transfers. + */ + csi->words_to_transfer = rounddown_pow_of_two(to_transfer); + + if (csi->bytes_per_word == 2) + csi->bytes_to_transfer = csi->words_to_transfer << 1; + else + csi->bytes_to_transfer = csi->words_to_transfer; +} + +static inline void rzv2m_csi_set_rx_fifo_trigger_level(struct rzv2m_csi_priv *csi) +{ + rzv2m_csi_reg_write_bit(csi, CSI_FIFOTRG, CSI_FIFOTRG_R_TRG, + ilog2(csi->words_to_transfer)); +} + +static inline void rzv2m_csi_enable_rx_trigger(struct rzv2m_csi_priv *csi, + bool enable) +{ + rzv2m_csi_reg_write_bit(csi, CSI_CNT, CSI_CNT_R_TRGEN, enable); +} + +static void rzv2m_csi_disable_irqs(const struct rzv2m_csi_priv *csi, + u32 enable_bits) +{ + u32 cnt = readl(csi->base + CSI_CNT); + + writel(cnt & ~enable_bits, csi->base + CSI_CNT); +} + +static void rzv2m_csi_disable_all_irqs(struct rzv2m_csi_priv *csi) +{ + rzv2m_csi_disable_irqs(csi, CSI_CNT_R_TRGR_E | CSI_CNT_T_TRGR_E | + CSI_CNT_CSIEND_E | CSI_CNT_TREND_E | + CSI_CNT_OVERF_E | CSI_CNT_UNDER_E); +} + +static inline void rzv2m_csi_clear_irqs(struct rzv2m_csi_priv *csi, u32 irqs) +{ + writel(irqs, csi->base + CSI_INT); +} + +static void rzv2m_csi_clear_all_irqs(struct rzv2m_csi_priv *csi) +{ + rzv2m_csi_clear_irqs(csi, CSI_INT_UNDER | CSI_INT_OVERF | + CSI_INT_TREND | CSI_INT_CSIEND | CSI_INT_T_TRGR | + CSI_INT_R_TRGR); +} + +static void rzv2m_csi_enable_irqs(struct rzv2m_csi_priv *csi, u32 enable_bits) +{ + u32 cnt = readl(csi->base + CSI_CNT); + + writel(cnt | enable_bits, csi->base + CSI_CNT); +} + +static int rzv2m_csi_wait_for_interrupt(struct rzv2m_csi_priv *csi, + u32 wait_mask, u32 enable_bits) +{ + int ret; + + rzv2m_csi_enable_irqs(csi, enable_bits); + + ret = wait_event_timeout(csi->wait, + ((csi->status & wait_mask) == wait_mask) || + csi->errors, HZ); + + rzv2m_csi_disable_irqs(csi, enable_bits); + + if (csi->errors) + return -EIO; + + if (!ret) + return -ETIMEDOUT; + + return 0; +} + +static int rzv2m_csi_wait_for_tx_empty(struct rzv2m_csi_priv *csi) +{ + int ret; + + if (readl(csi->base + CSI_OFIFOL) == 0) + return 0; + + ret = rzv2m_csi_wait_for_interrupt(csi, CSI_INT_TREND, CSI_CNT_TREND_E); + if (ret == -ETIMEDOUT) + csi->errors |= TX_TIMEOUT_ERROR; + + return ret; +} + +static inline int rzv2m_csi_wait_for_rx_ready(struct rzv2m_csi_priv *csi) +{ + int ret; + + if (readl(csi->base + CSI_IFIFOL) == csi->bytes_to_transfer) + return 0; + + ret = rzv2m_csi_wait_for_interrupt(csi, CSI_INT_R_TRGR, + CSI_CNT_R_TRGR_E); + if (ret == -ETIMEDOUT) + csi->errors |= RX_TIMEOUT_ERROR; + + return ret; +} + +static irqreturn_t rzv2m_csi_irq_handler(int irq, void *data) +{ + struct rzv2m_csi_priv *csi = data; + + csi->status = readl(csi->base + CSI_INT); + rzv2m_csi_disable_irqs(csi, csi->status); + + if (csi->status & CSI_INT_OVERF) + csi->errors |= OVERFLOW_ERROR; + if (csi->status & CSI_INT_UNDER) + csi->errors |= UNDERRUN_ERROR; + + wake_up(&csi->wait); + + return IRQ_HANDLED; +} + +static void rzv2m_csi_setup_clock(struct rzv2m_csi_priv *csi, u32 spi_hz) +{ + unsigned long csiclk_rate = clk_get_rate(csi->csiclk); + unsigned long pclk_rate = clk_get_rate(csi->pclk); + unsigned long csiclk_rate_limit = pclk_rate >> 1; + u32 cks; + + /* + * There is a restriction on the frequency of CSICLK, it has to be <= + * PCLK / 2. + */ + if (csiclk_rate > csiclk_rate_limit) { + clk_set_rate(csi->csiclk, csiclk_rate >> 1); + csiclk_rate = clk_get_rate(csi->csiclk); + } else if ((csiclk_rate << 1) <= csiclk_rate_limit) { + clk_set_rate(csi->csiclk, csiclk_rate << 1); + csiclk_rate = clk_get_rate(csi->csiclk); + } + + spi_hz = spi_hz > CSI_MAX_SPI_SCKO ? CSI_MAX_SPI_SCKO : spi_hz; + + cks = DIV_ROUND_UP(csiclk_rate, spi_hz << 1); + if (cks > CSI_CKS_MAX) + cks = CSI_CKS_MAX; + + dev_dbg(csi->dev, "SPI clk rate is %ldHz\n", csiclk_rate / (cks << 1)); + + rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_CKS, cks); +} + +static void rzv2m_csi_setup_operating_mode(struct rzv2m_csi_priv *csi, + struct spi_transfer *t) +{ + if (t->rx_buf && !t->tx_buf) + /* Reception-only mode */ + rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_TRMD, 0); + else + /* Send and receive mode */ + rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_TRMD, 1); + + csi->bytes_per_word = t->bits_per_word / 8; + rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_CCL, + csi->bytes_per_word == 2); +} + +static int rzv2m_csi_setup(struct spi_device *spi) +{ + struct rzv2m_csi_priv *csi = spi_controller_get_devdata(spi->controller); + int ret; + + rzv2m_csi_sw_reset(csi, 0); + + writel(CSI_MODE_SETUP, csi->base + CSI_MODE); + + /* Setup clock polarity and phase timing */ + rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_MODE, + ~spi->mode & SPI_MODE_X_MASK); + + /* Setup serial data order */ + rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_DIR, + !!(spi->mode & SPI_LSB_FIRST)); + + /* Set the operation mode as master */ + rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_SLAVE, 0); + + /* Give the IP a SW reset */ + ret = rzv2m_csi_sw_reset(csi, 1); + if (ret) + return ret; + rzv2m_csi_sw_reset(csi, 0); + + /* + * We need to enable the communication so that the clock will settle + * for the right polarity before enabling the CS. + */ + rzv2m_csi_start_stop_operation(csi, 1, false); + udelay(10); + rzv2m_csi_start_stop_operation(csi, 0, false); + + return 0; +} + +static int rzv2m_csi_pio_transfer(struct rzv2m_csi_priv *csi) +{ + bool tx_completed = !csi->txbuf; + bool rx_completed = !csi->rxbuf; + int ret = 0; + + /* Make sure the TX FIFO is empty */ + writel(0, csi->base + CSI_OFIFOL); + + csi->bytes_sent = 0; + csi->bytes_received = 0; + csi->errors = 0; + + rzv2m_csi_disable_all_irqs(csi); + rzv2m_csi_clear_all_irqs(csi); + rzv2m_csi_enable_rx_trigger(csi, true); + + while (!tx_completed || !rx_completed) { + /* + * Decide how many words we are going to transfer during + * this cycle (for both TX and RX), then set the RX FIFO trigger + * level accordingly. No need to set a trigger level for the + * TX FIFO, as this IP comes with an interrupt that fires when + * the TX FIFO is empty. + */ + rzv2m_csi_calc_current_transfer(csi); + rzv2m_csi_set_rx_fifo_trigger_level(csi); + + rzv2m_csi_enable_irqs(csi, CSI_INT_OVERF | CSI_INT_UNDER); + + /* Make sure the RX FIFO is empty */ + writel(0, csi->base + CSI_IFIFOL); + + writel(readl(csi->base + CSI_INT), csi->base + CSI_INT); + csi->status = 0; + + rzv2m_csi_start_stop_operation(csi, 1, false); + + /* TX */ + if (csi->txbuf) { + ret = rzv2m_csi_fill_txfifo(csi); + if (ret) + break; + + ret = rzv2m_csi_wait_for_tx_empty(csi); + if (ret) + break; + + if (csi->bytes_sent == csi->buffer_len) + tx_completed = true; + } + + /* + * Make sure the RX FIFO contains the desired number of words. + * We then either flush its content, or we copy it onto + * csi->rxbuf. + */ + ret = rzv2m_csi_wait_for_rx_ready(csi); + if (ret) + break; + + /* RX */ + if (csi->rxbuf) { + rzv2m_csi_start_stop_operation(csi, 0, false); + + ret = rzv2m_csi_read_rxfifo(csi); + if (ret) + break; + + if (csi->bytes_received == csi->buffer_len) + rx_completed = true; + } + + ret = rzv2m_csi_start_stop_operation(csi, 0, true); + if (ret) + goto pio_quit; + + if (csi->errors) { + ret = -EIO; + goto pio_quit; + } + } + + rzv2m_csi_start_stop_operation(csi, 0, true); + +pio_quit: + rzv2m_csi_disable_all_irqs(csi); + rzv2m_csi_enable_rx_trigger(csi, false); + rzv2m_csi_clear_all_irqs(csi); + + return ret; +} + +static int rzv2m_csi_transfer_one(struct spi_controller *controller, + struct spi_device *spi, + struct spi_transfer *transfer) +{ + struct rzv2m_csi_priv *csi = spi_controller_get_devdata(controller); + struct device *dev = csi->dev; + int ret; + + csi->txbuf = transfer->tx_buf; + csi->rxbuf = transfer->rx_buf; + csi->buffer_len = transfer->len; + + rzv2m_csi_setup_operating_mode(csi, transfer); + + rzv2m_csi_setup_clock(csi, transfer->speed_hz); + + ret = rzv2m_csi_pio_transfer(csi); + if (ret) { + if (csi->errors & UNDERRUN_ERROR) + dev_err(dev, "Underrun error\n"); + if (csi->errors & OVERFLOW_ERROR) + dev_err(dev, "Overflow error\n"); + if (csi->errors & TX_TIMEOUT_ERROR) + dev_err(dev, "TX timeout error\n"); + if (csi->errors & RX_TIMEOUT_ERROR) + dev_err(dev, "RX timeout error\n"); + } + + return ret; +} + +static int rzv2m_csi_probe(struct platform_device *pdev) +{ + struct spi_controller *controller; + struct device *dev = &pdev->dev; + struct rzv2m_csi_priv *csi; + struct reset_control *rstc; + int irq; + int ret; + + controller = devm_spi_alloc_host(dev, sizeof(*csi)); + if (!controller) + return -ENOMEM; + + csi = spi_controller_get_devdata(controller); + platform_set_drvdata(pdev, csi); + + csi->dev = dev; + csi->controller = controller; + + csi->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(csi->base)) + return PTR_ERR(csi->base); + + irq = platform_get_irq(pdev, 0); + if (irq < 0) + return irq; + + csi->csiclk = devm_clk_get(dev, "csiclk"); + if (IS_ERR(csi->csiclk)) + return dev_err_probe(dev, PTR_ERR(csi->csiclk), + "could not get csiclk\n"); + + csi->pclk = devm_clk_get(dev, "pclk"); + if (IS_ERR(csi->pclk)) + return dev_err_probe(dev, PTR_ERR(csi->pclk), + "could not get pclk\n"); + + rstc = devm_reset_control_get_shared(dev, NULL); + if (IS_ERR(rstc)) + return dev_err_probe(dev, PTR_ERR(rstc), "Missing reset ctrl\n"); + + init_waitqueue_head(&csi->wait); + + controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST; + controller->bits_per_word_mask = SPI_BPW_MASK(16) | SPI_BPW_MASK(8); + controller->setup = rzv2m_csi_setup; + controller->transfer_one = rzv2m_csi_transfer_one; + controller->use_gpio_descriptors = true; + + device_set_node(&controller->dev, dev_fwnode(dev)); + + ret = devm_request_irq(dev, irq, rzv2m_csi_irq_handler, 0, + dev_name(dev), csi); + if (ret) + return dev_err_probe(dev, ret, "cannot request IRQ\n"); + + /* + * The reset also affects other HW that is not under the control + * of Linux. Therefore, all we can do is make sure the reset is + * deasserted. + */ + reset_control_deassert(rstc); + + /* Make sure the IP is in SW reset state */ + ret = rzv2m_csi_sw_reset(csi, 1); + if (ret) + return ret; + + ret = clk_prepare_enable(csi->csiclk); + if (ret) + return dev_err_probe(dev, ret, "could not enable csiclk\n"); + + ret = spi_register_controller(controller); + if (ret) { + clk_disable_unprepare(csi->csiclk); + return dev_err_probe(dev, ret, "register controller failed\n"); + } + + return 0; +} + +static void rzv2m_csi_remove(struct platform_device *pdev) +{ + struct rzv2m_csi_priv *csi = platform_get_drvdata(pdev); + + spi_unregister_controller(csi->controller); + rzv2m_csi_sw_reset(csi, 1); + clk_disable_unprepare(csi->csiclk); +} + +static const struct of_device_id rzv2m_csi_match[] = { + { .compatible = "renesas,rzv2m-csi" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, rzv2m_csi_match); + +static struct platform_driver rzv2m_csi_drv = { + .probe = rzv2m_csi_probe, + .remove_new = rzv2m_csi_remove, + .driver = { + .name = "rzv2m_csi", + .of_match_table = rzv2m_csi_match, + }, +}; +module_platform_driver(rzv2m_csi_drv); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Fabrizio Castro <castro.fabrizio.jz@renesas.com>"); +MODULE_DESCRIPTION("Clocked Serial Interface Driver"); |