/* * Cadence SPI controller driver (master mode only) * * Copyright (C) 2008 - 2014 Xilinx, Inc. * * based on Blackfin On-Chip SPI Driver (spi_bfin5xx.c) * * This program is free software; you can redistribute it and/or modify it under * the terms of the GNU General Public License version 2 as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. */ #include <linux/clk.h> #include <linux/delay.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/module.h> #include <linux/of_irq.h> #include <linux/of_address.h> #include <linux/platform_device.h> #include <linux/spi/spi.h> /* Name of this driver */ #define CDNS_SPI_NAME "cdns-spi" /* Register offset definitions */ #define CDNS_SPI_CR_OFFSET 0x00 /* Configuration Register, RW */ #define CDNS_SPI_ISR_OFFSET 0x04 /* Interrupt Status Register, RO */ #define CDNS_SPI_IER_OFFSET 0x08 /* Interrupt Enable Register, WO */ #define CDNS_SPI_IDR_OFFSET 0x0c /* Interrupt Disable Register, WO */ #define CDNS_SPI_IMR_OFFSET 0x10 /* Interrupt Enabled Mask Register, RO */ #define CDNS_SPI_ER_OFFSET 0x14 /* Enable/Disable Register, RW */ #define CDNS_SPI_DR_OFFSET 0x18 /* Delay Register, RW */ #define CDNS_SPI_TXD_OFFSET 0x1C /* Data Transmit Register, WO */ #define CDNS_SPI_RXD_OFFSET 0x20 /* Data Receive Register, RO */ #define CDNS_SPI_SICR_OFFSET 0x24 /* Slave Idle Count Register, RW */ #define CDNS_SPI_THLD_OFFSET 0x28 /* Transmit FIFO Watermark Register,RW */ /* * SPI Configuration Register bit Masks * * This register contains various control bits that affect the operation * of the SPI controller */ #define CDNS_SPI_CR_MANSTRT_MASK 0x00010000 /* Manual TX Start */ #define CDNS_SPI_CR_CPHA_MASK 0x00000004 /* Clock Phase Control */ #define CDNS_SPI_CR_CPOL_MASK 0x00000002 /* Clock Polarity Control */ #define CDNS_SPI_CR_SSCTRL_MASK 0x00003C00 /* Slave Select Mask */ #define CDNS_SPI_CR_PERI_SEL_MASK 0x00000200 /* Peripheral Select Decode */ #define CDNS_SPI_CR_BAUD_DIV_MASK 0x00000038 /* Baud Rate Divisor Mask */ #define CDNS_SPI_CR_MSTREN_MASK 0x00000001 /* Master Enable Mask */ #define CDNS_SPI_CR_MANSTRTEN_MASK 0x00008000 /* Manual TX Enable Mask */ #define CDNS_SPI_CR_SSFORCE_MASK 0x00004000 /* Manual SS Enable Mask */ #define CDNS_SPI_CR_BAUD_DIV_4_MASK 0x00000008 /* Default Baud Div Mask */ #define CDNS_SPI_CR_DEFAULT_MASK (CDNS_SPI_CR_MSTREN_MASK | \ CDNS_SPI_CR_SSCTRL_MASK | \ CDNS_SPI_CR_SSFORCE_MASK | \ CDNS_SPI_CR_BAUD_DIV_4_MASK) /* * SPI Configuration Register - Baud rate and slave select * * These are the values used in the calculation of baud rate divisor and * setting the slave select. */ #define CDNS_SPI_BAUD_DIV_MAX 7 /* Baud rate divisor maximum */ #define CDNS_SPI_BAUD_DIV_MIN 1 /* Baud rate divisor minimum */ #define CDNS_SPI_BAUD_DIV_SHIFT 3 /* Baud rate divisor shift in CR */ #define CDNS_SPI_SS_SHIFT 10 /* Slave Select field shift in CR */ #define CDNS_SPI_SS0 0x1 /* Slave Select zero */ /* * SPI Interrupt Registers bit Masks * * All the four interrupt registers (Status/Mask/Enable/Disable) have the same * bit definitions. */ #define CDNS_SPI_IXR_TXOW_MASK 0x00000004 /* SPI TX FIFO Overwater */ #define CDNS_SPI_IXR_MODF_MASK 0x00000002 /* SPI Mode Fault */ #define CDNS_SPI_IXR_RXNEMTY_MASK 0x00000010 /* SPI RX FIFO Not Empty */ #define CDNS_SPI_IXR_DEFAULT_MASK (CDNS_SPI_IXR_TXOW_MASK | \ CDNS_SPI_IXR_MODF_MASK) #define CDNS_SPI_IXR_TXFULL_MASK 0x00000008 /* SPI TX Full */ #define CDNS_SPI_IXR_ALL_MASK 0x0000007F /* SPI all interrupts */ /* * SPI Enable Register bit Masks * * This register is used to enable or disable the SPI controller */ #define CDNS_SPI_ER_ENABLE_MASK 0x00000001 /* SPI Enable Bit Mask */ #define CDNS_SPI_ER_DISABLE_MASK 0x0 /* SPI Disable Bit Mask */ /* SPI FIFO depth in bytes */ #define CDNS_SPI_FIFO_DEPTH 128 /* Default number of chip select lines */ #define CDNS_SPI_DEFAULT_NUM_CS 4 /** * struct cdns_spi - This definition defines spi driver instance * @regs: Virtual address of the SPI controller registers * @ref_clk: Pointer to the peripheral clock * @pclk: Pointer to the APB clock * @speed_hz: Current SPI bus clock speed in Hz * @txbuf: Pointer to the TX buffer * @rxbuf: Pointer to the RX buffer * @tx_bytes: Number of bytes left to transfer * @rx_bytes: Number of bytes requested * @dev_busy: Device busy flag * @is_decoded_cs: Flag for decoder property set or not */ struct cdns_spi { void __iomem *regs; struct clk *ref_clk; struct clk *pclk; u32 speed_hz; const u8 *txbuf; u8 *rxbuf; int tx_bytes; int rx_bytes; u8 dev_busy; u32 is_decoded_cs; }; /* Macros for the SPI controller read/write */ static inline u32 cdns_spi_read(struct cdns_spi *xspi, u32 offset) { return readl_relaxed(xspi->regs + offset); } static inline void cdns_spi_write(struct cdns_spi *xspi, u32 offset, u32 val) { writel_relaxed(val, xspi->regs + offset); } /** * cdns_spi_init_hw - Initialize the hardware and configure the SPI controller * @xspi: Pointer to the cdns_spi structure * * On reset the SPI controller is configured to be in master mode, baud rate * divisor is set to 4, threshold value for TX FIFO not full interrupt is set * to 1 and size of the word to be transferred as 8 bit. * This function initializes the SPI controller to disable and clear all the * interrupts, enable manual slave select and manual start, deselect all the * chip select lines, and enable the SPI controller. */ static void cdns_spi_init_hw(struct cdns_spi *xspi) { u32 ctrl_reg = CDNS_SPI_CR_DEFAULT_MASK; if (xspi->is_decoded_cs) ctrl_reg |= CDNS_SPI_CR_PERI_SEL_MASK; cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, CDNS_SPI_ER_DISABLE_MASK); cdns_spi_write(xspi, CDNS_SPI_IDR_OFFSET, CDNS_SPI_IXR_ALL_MASK); /* Clear the RX FIFO */ while (cdns_spi_read(xspi, CDNS_SPI_ISR_OFFSET) & CDNS_SPI_IXR_RXNEMTY_MASK) cdns_spi_read(xspi, CDNS_SPI_RXD_OFFSET); cdns_spi_write(xspi, CDNS_SPI_ISR_OFFSET, CDNS_SPI_IXR_ALL_MASK); cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, ctrl_reg); cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, CDNS_SPI_ER_ENABLE_MASK); } /** * cdns_spi_chipselect - Select or deselect the chip select line * @spi: Pointer to the spi_device structure * @is_on: Select(0) or deselect (1) the chip select line */ static void cdns_spi_chipselect(struct spi_device *spi, bool is_high) { struct cdns_spi *xspi = spi_master_get_devdata(spi->master); u32 ctrl_reg; ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET); if (is_high) { /* Deselect the slave */ ctrl_reg |= CDNS_SPI_CR_SSCTRL_MASK; } else { /* Select the slave */ ctrl_reg &= ~CDNS_SPI_CR_SSCTRL_MASK; if (!(xspi->is_decoded_cs)) ctrl_reg |= ((~(CDNS_SPI_SS0 << spi->chip_select)) << CDNS_SPI_SS_SHIFT) & CDNS_SPI_CR_SSCTRL_MASK; else ctrl_reg |= (spi->chip_select << CDNS_SPI_SS_SHIFT) & CDNS_SPI_CR_SSCTRL_MASK; } cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, ctrl_reg); } /** * cdns_spi_config_clock_mode - Sets clock polarity and phase * @spi: Pointer to the spi_device structure * * Sets the requested clock polarity and phase. */ static void cdns_spi_config_clock_mode(struct spi_device *spi) { struct cdns_spi *xspi = spi_master_get_devdata(spi->master); u32 ctrl_reg, new_ctrl_reg; new_ctrl_reg = ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET); /* Set the SPI clock phase and clock polarity */ new_ctrl_reg &= ~(CDNS_SPI_CR_CPHA_MASK | CDNS_SPI_CR_CPOL_MASK); if (spi->mode & SPI_CPHA) new_ctrl_reg |= CDNS_SPI_CR_CPHA_MASK; if (spi->mode & SPI_CPOL) new_ctrl_reg |= CDNS_SPI_CR_CPOL_MASK; if (new_ctrl_reg != ctrl_reg) { /* * Just writing the CR register does not seem to apply the clock * setting changes. This is problematic when changing the clock * polarity as it will cause the SPI slave to see spurious clock * transitions. To workaround the issue toggle the ER register. */ cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, CDNS_SPI_ER_DISABLE_MASK); cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, new_ctrl_reg); cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, CDNS_SPI_ER_ENABLE_MASK); } } /** * cdns_spi_config_clock_freq - Sets clock frequency * @spi: Pointer to the spi_device structure * @transfer: Pointer to the spi_transfer structure which provides * information about next transfer setup parameters * * Sets the requested clock frequency. * Note: If the requested frequency is not an exact match with what can be * obtained using the prescalar value the driver sets the clock frequency which * is lower than the requested frequency (maximum lower) for the transfer. If * the requested frequency is higher or lower than that is supported by the SPI * controller the driver will set the highest or lowest frequency supported by * controller. */ static void cdns_spi_config_clock_freq(struct spi_device *spi, struct spi_transfer *transfer) { struct cdns_spi *xspi = spi_master_get_devdata(spi->master); u32 ctrl_reg, baud_rate_val; unsigned long frequency; frequency = clk_get_rate(xspi->ref_clk); ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET); /* Set the clock frequency */ if (xspi->speed_hz != transfer->speed_hz) { /* first valid value is 1 */ baud_rate_val = CDNS_SPI_BAUD_DIV_MIN; while ((baud_rate_val < CDNS_SPI_BAUD_DIV_MAX) && (frequency / (2 << baud_rate_val)) > transfer->speed_hz) baud_rate_val++; ctrl_reg &= ~CDNS_SPI_CR_BAUD_DIV_MASK; ctrl_reg |= baud_rate_val << CDNS_SPI_BAUD_DIV_SHIFT; xspi->speed_hz = frequency / (2 << baud_rate_val); } cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, ctrl_reg); } /** * cdns_spi_setup_transfer - Configure SPI controller for specified transfer * @spi: Pointer to the spi_device structure * @transfer: Pointer to the spi_transfer structure which provides * information about next transfer setup parameters * * Sets the operational mode of SPI controller for the next SPI transfer and * sets the requested clock frequency. * * Return: Always 0 */ static int cdns_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *transfer) { struct cdns_spi *xspi = spi_master_get_devdata(spi->master); cdns_spi_config_clock_freq(spi, transfer); dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u clock speed\n", __func__, spi->mode, spi->bits_per_word, xspi->speed_hz); return 0; } /** * cdns_spi_fill_tx_fifo - Fills the TX FIFO with as many bytes as possible * @xspi: Pointer to the cdns_spi structure */ static void cdns_spi_fill_tx_fifo(struct cdns_spi *xspi) { unsigned long trans_cnt = 0; while ((trans_cnt < CDNS_SPI_FIFO_DEPTH) && (xspi->tx_bytes > 0)) { if (xspi->txbuf) cdns_spi_write(xspi, CDNS_SPI_TXD_OFFSET, *xspi->txbuf++); else cdns_spi_write(xspi, CDNS_SPI_TXD_OFFSET, 0); xspi->tx_bytes--; trans_cnt++; } } /** * cdns_spi_irq - Interrupt service routine of the SPI controller * @irq: IRQ number * @dev_id: Pointer to the xspi structure * * This function handles TX empty and Mode Fault interrupts only. * On TX empty interrupt this function reads the received data from RX FIFO and * fills the TX FIFO if there is any data remaining to be transferred. * On Mode Fault interrupt this function indicates that transfer is completed, * the SPI subsystem will identify the error as the remaining bytes to be * transferred is non-zero. * * Return: IRQ_HANDLED when handled; IRQ_NONE otherwise. */ static irqreturn_t cdns_spi_irq(int irq, void *dev_id) { struct spi_master *master = dev_id; struct cdns_spi *xspi = spi_master_get_devdata(master); u32 intr_status, status; status = IRQ_NONE; intr_status = cdns_spi_read(xspi, CDNS_SPI_ISR_OFFSET); cdns_spi_write(xspi, CDNS_SPI_ISR_OFFSET, intr_status); if (intr_status & CDNS_SPI_IXR_MODF_MASK) { /* Indicate that transfer is completed, the SPI subsystem will * identify the error as the remaining bytes to be * transferred is non-zero */ cdns_spi_write(xspi, CDNS_SPI_IDR_OFFSET, CDNS_SPI_IXR_DEFAULT_MASK); spi_finalize_current_transfer(master); status = IRQ_HANDLED; } else if (intr_status & CDNS_SPI_IXR_TXOW_MASK) { unsigned long trans_cnt; trans_cnt = xspi->rx_bytes - xspi->tx_bytes; /* Read out the data from the RX FIFO */ while (trans_cnt) { u8 data; data = cdns_spi_read(xspi, CDNS_SPI_RXD_OFFSET); if (xspi->rxbuf) *xspi->rxbuf++ = data; xspi->rx_bytes--; trans_cnt--; } if (xspi->tx_bytes) { /* There is more data to send */ cdns_spi_fill_tx_fifo(xspi); } else { /* Transfer is completed */ cdns_spi_write(xspi, CDNS_SPI_IDR_OFFSET, CDNS_SPI_IXR_DEFAULT_MASK); spi_finalize_current_transfer(master); } status = IRQ_HANDLED; } return status; } static int cdns_prepare_message(struct spi_master *master, struct spi_message *msg) { cdns_spi_config_clock_mode(msg->spi); return 0; } /** * cdns_transfer_one - Initiates the SPI transfer * @master: Pointer to spi_master structure * @spi: Pointer to the spi_device structure * @transfer: Pointer to the spi_transfer structure which provides * information about next transfer parameters * * This function fills the TX FIFO, starts the SPI transfer and * returns a positive transfer count so that core will wait for completion. * * Return: Number of bytes transferred in the last transfer */ static int cdns_transfer_one(struct spi_master *master, struct spi_device *spi, struct spi_transfer *transfer) { struct cdns_spi *xspi = spi_master_get_devdata(master); xspi->txbuf = transfer->tx_buf; xspi->rxbuf = transfer->rx_buf; xspi->tx_bytes = transfer->len; xspi->rx_bytes = transfer->len; cdns_spi_setup_transfer(spi, transfer); cdns_spi_fill_tx_fifo(xspi); cdns_spi_write(xspi, CDNS_SPI_IER_OFFSET, CDNS_SPI_IXR_DEFAULT_MASK); return transfer->len; } /** * cdns_prepare_transfer_hardware - Prepares hardware for transfer. * @master: Pointer to the spi_master structure which provides * information about the controller. * * This function enables SPI master controller. * * Return: 0 always */ static int cdns_prepare_transfer_hardware(struct spi_master *master) { struct cdns_spi *xspi = spi_master_get_devdata(master); cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, CDNS_SPI_ER_ENABLE_MASK); return 0; } /** * cdns_unprepare_transfer_hardware - Relaxes hardware after transfer * @master: Pointer to the spi_master structure which provides * information about the controller. * * This function disables the SPI master controller. * * Return: 0 always */ static int cdns_unprepare_transfer_hardware(struct spi_master *master) { struct cdns_spi *xspi = spi_master_get_devdata(master); cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, CDNS_SPI_ER_DISABLE_MASK); return 0; } /** * cdns_spi_probe - Probe method for the SPI driver * @pdev: Pointer to the platform_device structure * * This function initializes the driver data structures and the hardware. * * Return: 0 on success and error value on error */ static int cdns_spi_probe(struct platform_device *pdev) { int ret = 0, irq; struct spi_master *master; struct cdns_spi *xspi; struct resource *res; u32 num_cs; master = spi_alloc_master(&pdev->dev, sizeof(*xspi)); if (master == NULL) return -ENOMEM; xspi = spi_master_get_devdata(master); master->dev.of_node = pdev->dev.of_node; platform_set_drvdata(pdev, master); res = platform_get_resource(pdev, IORESOURCE_MEM, 0); xspi->regs = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(xspi->regs)) { ret = PTR_ERR(xspi->regs); goto remove_master; } xspi->pclk = devm_clk_get(&pdev->dev, "pclk"); if (IS_ERR(xspi->pclk)) { dev_err(&pdev->dev, "pclk clock not found.\n"); ret = PTR_ERR(xspi->pclk); goto remove_master; } xspi->ref_clk = devm_clk_get(&pdev->dev, "ref_clk"); if (IS_ERR(xspi->ref_clk)) { dev_err(&pdev->dev, "ref_clk clock not found.\n"); ret = PTR_ERR(xspi->ref_clk); goto remove_master; } ret = clk_prepare_enable(xspi->pclk); if (ret) { dev_err(&pdev->dev, "Unable to enable APB clock.\n"); goto remove_master; } ret = clk_prepare_enable(xspi->ref_clk); if (ret) { dev_err(&pdev->dev, "Unable to enable device clock.\n"); goto clk_dis_apb; } ret = of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs); if (ret < 0) master->num_chipselect = CDNS_SPI_DEFAULT_NUM_CS; else master->num_chipselect = num_cs; ret = of_property_read_u32(pdev->dev.of_node, "is-decoded-cs", &xspi->is_decoded_cs); if (ret < 0) xspi->is_decoded_cs = 0; /* SPI controller initializations */ cdns_spi_init_hw(xspi); irq = platform_get_irq(pdev, 0); if (irq <= 0) { ret = -ENXIO; dev_err(&pdev->dev, "irq number is invalid\n"); goto remove_master; } ret = devm_request_irq(&pdev->dev, irq, cdns_spi_irq, 0, pdev->name, master); if (ret != 0) { ret = -ENXIO; dev_err(&pdev->dev, "request_irq failed\n"); goto remove_master; } master->prepare_transfer_hardware = cdns_prepare_transfer_hardware; master->prepare_message = cdns_prepare_message; master->transfer_one = cdns_transfer_one; master->unprepare_transfer_hardware = cdns_unprepare_transfer_hardware; master->set_cs = cdns_spi_chipselect; master->mode_bits = SPI_CPOL | SPI_CPHA; /* Set to default valid value */ master->max_speed_hz = clk_get_rate(xspi->ref_clk) / 4; xspi->speed_hz = master->max_speed_hz; master->bits_per_word_mask = SPI_BPW_MASK(8); ret = spi_register_master(master); if (ret) { dev_err(&pdev->dev, "spi_register_master failed\n"); goto clk_dis_all; } return ret; clk_dis_all: clk_disable_unprepare(xspi->ref_clk); clk_dis_apb: clk_disable_unprepare(xspi->pclk); remove_master: spi_master_put(master); return ret; } /** * cdns_spi_remove - Remove method for the SPI driver * @pdev: Pointer to the platform_device structure * * This function is called if a device is physically removed from the system or * if the driver module is being unloaded. It frees all resources allocated to * the device. * * Return: 0 on success and error value on error */ static int cdns_spi_remove(struct platform_device *pdev) { struct spi_master *master = platform_get_drvdata(pdev); struct cdns_spi *xspi = spi_master_get_devdata(master); cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, CDNS_SPI_ER_DISABLE_MASK); clk_disable_unprepare(xspi->ref_clk); clk_disable_unprepare(xspi->pclk); spi_unregister_master(master); return 0; } /** * cdns_spi_suspend - Suspend method for the SPI driver * @dev: Address of the platform_device structure * * This function disables the SPI controller and * changes the driver state to "suspend" * * Return: Always 0 */ static int __maybe_unused cdns_spi_suspend(struct device *dev) { struct platform_device *pdev = container_of(dev, struct platform_device, dev); struct spi_master *master = platform_get_drvdata(pdev); struct cdns_spi *xspi = spi_master_get_devdata(master); spi_master_suspend(master); clk_disable_unprepare(xspi->ref_clk); clk_disable_unprepare(xspi->pclk); return 0; } /** * cdns_spi_resume - Resume method for the SPI driver * @dev: Address of the platform_device structure * * This function changes the driver state to "ready" * * Return: 0 on success and error value on error */ static int __maybe_unused cdns_spi_resume(struct device *dev) { struct platform_device *pdev = container_of(dev, struct platform_device, dev); struct spi_master *master = platform_get_drvdata(pdev); struct cdns_spi *xspi = spi_master_get_devdata(master); int ret = 0; ret = clk_prepare_enable(xspi->pclk); if (ret) { dev_err(dev, "Cannot enable APB clock.\n"); return ret; } ret = clk_prepare_enable(xspi->ref_clk); if (ret) { dev_err(dev, "Cannot enable device clock.\n"); clk_disable(xspi->pclk); return ret; } spi_master_resume(master); return 0; } static SIMPLE_DEV_PM_OPS(cdns_spi_dev_pm_ops, cdns_spi_suspend, cdns_spi_resume); static const struct of_device_id cdns_spi_of_match[] = { { .compatible = "xlnx,zynq-spi-r1p6" }, { .compatible = "cdns,spi-r1p6" }, { /* end of table */ } }; MODULE_DEVICE_TABLE(of, cdns_spi_of_match); /* cdns_spi_driver - This structure defines the SPI subsystem platform driver */ static struct platform_driver cdns_spi_driver = { .probe = cdns_spi_probe, .remove = cdns_spi_remove, .driver = { .name = CDNS_SPI_NAME, .of_match_table = cdns_spi_of_match, .pm = &cdns_spi_dev_pm_ops, }, }; module_platform_driver(cdns_spi_driver); MODULE_AUTHOR("Xilinx, Inc."); MODULE_DESCRIPTION("Cadence SPI driver"); MODULE_LICENSE("GPL");