2 * Cadence SPI controller driver (master mode only)
4 * Copyright (C) 2008 - 2014 Xilinx, Inc.
6 * based on Blackfin On-Chip SPI Driver (spi_bfin5xx.c)
8 * This program is free software; you can redistribute it and/or modify it under
9 * the terms of the GNU General Public License version 2 as published by the
10 * Free Software Foundation; either version 2 of the License, or (at your
11 * option) any later version.
14 #include <linux/clk.h>
15 #include <linux/delay.h>
16 #include <linux/interrupt.h>
18 #include <linux/module.h>
19 #include <linux/of_irq.h>
20 #include <linux/of_address.h>
21 #include <linux/platform_device.h>
22 #include <linux/spi/spi.h>
24 /* Name of this driver */
25 #define CDNS_SPI_NAME "cdns-spi"
27 /* Register offset definitions */
28 #define CDNS_SPI_CR_OFFSET 0x00 /* Configuration Register, RW */
29 #define CDNS_SPI_ISR_OFFSET 0x04 /* Interrupt Status Register, RO */
30 #define CDNS_SPI_IER_OFFSET 0x08 /* Interrupt Enable Register, WO */
31 #define CDNS_SPI_IDR_OFFSET 0x0c /* Interrupt Disable Register, WO */
32 #define CDNS_SPI_IMR_OFFSET 0x10 /* Interrupt Enabled Mask Register, RO */
33 #define CDNS_SPI_ER_OFFSET 0x14 /* Enable/Disable Register, RW */
34 #define CDNS_SPI_DR_OFFSET 0x18 /* Delay Register, RW */
35 #define CDNS_SPI_TXD_OFFSET 0x1C /* Data Transmit Register, WO */
36 #define CDNS_SPI_RXD_OFFSET 0x20 /* Data Receive Register, RO */
37 #define CDNS_SPI_SICR_OFFSET 0x24 /* Slave Idle Count Register, RW */
38 #define CDNS_SPI_THLD_OFFSET 0x28 /* Transmit FIFO Watermark Register,RW */
41 * SPI Configuration Register bit Masks
43 * This register contains various control bits that affect the operation
44 * of the SPI controller
46 #define CDNS_SPI_CR_MANSTRT_MASK 0x00010000 /* Manual TX Start */
47 #define CDNS_SPI_CR_CPHA_MASK 0x00000004 /* Clock Phase Control */
48 #define CDNS_SPI_CR_CPOL_MASK 0x00000002 /* Clock Polarity Control */
49 #define CDNS_SPI_CR_SSCTRL_MASK 0x00003C00 /* Slave Select Mask */
50 #define CDNS_SPI_CR_BAUD_DIV_MASK 0x00000038 /* Baud Rate Divisor Mask */
51 #define CDNS_SPI_CR_MSTREN_MASK 0x00000001 /* Master Enable Mask */
52 #define CDNS_SPI_CR_MANSTRTEN_MASK 0x00008000 /* Manual TX Enable Mask */
53 #define CDNS_SPI_CR_SSFORCE_MASK 0x00004000 /* Manual SS Enable Mask */
54 #define CDNS_SPI_CR_BAUD_DIV_4_MASK 0x00000008 /* Default Baud Div Mask */
55 #define CDNS_SPI_CR_DEFAULT_MASK (CDNS_SPI_CR_MSTREN_MASK | \
56 CDNS_SPI_CR_SSCTRL_MASK | \
57 CDNS_SPI_CR_SSFORCE_MASK | \
58 CDNS_SPI_CR_BAUD_DIV_4_MASK)
61 * SPI Configuration Register - Baud rate and slave select
63 * These are the values used in the calculation of baud rate divisor and
64 * setting the slave select.
67 #define CDNS_SPI_BAUD_DIV_MAX 7 /* Baud rate divisor maximum */
68 #define CDNS_SPI_BAUD_DIV_MIN 1 /* Baud rate divisor minimum */
69 #define CDNS_SPI_BAUD_DIV_SHIFT 3 /* Baud rate divisor shift in CR */
70 #define CDNS_SPI_SS_SHIFT 10 /* Slave Select field shift in CR */
71 #define CDNS_SPI_SS0 0x1 /* Slave Select zero */
74 * SPI Interrupt Registers bit Masks
76 * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
79 #define CDNS_SPI_IXR_TXOW_MASK 0x00000004 /* SPI TX FIFO Overwater */
80 #define CDNS_SPI_IXR_MODF_MASK 0x00000002 /* SPI Mode Fault */
81 #define CDNS_SPI_IXR_RXNEMTY_MASK 0x00000010 /* SPI RX FIFO Not Empty */
82 #define CDNS_SPI_IXR_DEFAULT_MASK (CDNS_SPI_IXR_TXOW_MASK | \
83 CDNS_SPI_IXR_MODF_MASK)
84 #define CDNS_SPI_IXR_TXFULL_MASK 0x00000008 /* SPI TX Full */
85 #define CDNS_SPI_IXR_ALL_MASK 0x0000007F /* SPI all interrupts */
88 * SPI Enable Register bit Masks
90 * This register is used to enable or disable the SPI controller
92 #define CDNS_SPI_ER_ENABLE_MASK 0x00000001 /* SPI Enable Bit Mask */
93 #define CDNS_SPI_ER_DISABLE_MASK 0x0 /* SPI Disable Bit Mask */
95 /* SPI FIFO depth in bytes */
96 #define CDNS_SPI_FIFO_DEPTH 128
98 /* Default number of chip select lines */
99 #define CDNS_SPI_DEFAULT_NUM_CS 4
102 * struct cdns_spi - This definition defines spi driver instance
103 * @regs: Virtual address of the SPI controller registers
104 * @ref_clk: Pointer to the peripheral clock
105 * @pclk: Pointer to the APB clock
106 * @speed_hz: Current SPI bus clock speed in Hz
107 * @txbuf: Pointer to the TX buffer
108 * @rxbuf: Pointer to the RX buffer
109 * @tx_bytes: Number of bytes left to transfer
110 * @rx_bytes: Number of bytes requested
111 * @dev_busy: Device busy flag
112 * @is_decoded_cs: Flag for decoder property set or not
127 /* Macros for the SPI controller read/write */
128 static inline u32 cdns_spi_read(struct cdns_spi *xspi, u32 offset)
130 return readl_relaxed(xspi->regs + offset);
133 static inline void cdns_spi_write(struct cdns_spi *xspi, u32 offset, u32 val)
135 writel_relaxed(val, xspi->regs + offset);
139 * cdns_spi_init_hw - Initialize the hardware and configure the SPI controller
140 * @xspi: Pointer to the cdns_spi structure
142 * On reset the SPI controller is configured to be in master mode, baud rate
143 * divisor is set to 4, threshold value for TX FIFO not full interrupt is set
144 * to 1 and size of the word to be transferred as 8 bit.
145 * This function initializes the SPI controller to disable and clear all the
146 * interrupts, enable manual slave select and manual start, deselect all the
147 * chip select lines, and enable the SPI controller.
149 static void cdns_spi_init_hw(struct cdns_spi *xspi)
151 cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
152 CDNS_SPI_ER_DISABLE_MASK);
153 cdns_spi_write(xspi, CDNS_SPI_IDR_OFFSET,
154 CDNS_SPI_IXR_ALL_MASK);
156 /* Clear the RX FIFO */
157 while (cdns_spi_read(xspi, CDNS_SPI_ISR_OFFSET) &
158 CDNS_SPI_IXR_RXNEMTY_MASK)
159 cdns_spi_read(xspi, CDNS_SPI_RXD_OFFSET);
161 cdns_spi_write(xspi, CDNS_SPI_ISR_OFFSET,
162 CDNS_SPI_IXR_ALL_MASK);
163 cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET,
164 CDNS_SPI_CR_DEFAULT_MASK);
165 cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
166 CDNS_SPI_ER_ENABLE_MASK);
170 * cdns_spi_chipselect - Select or deselect the chip select line
171 * @spi: Pointer to the spi_device structure
172 * @is_on: Select(0) or deselect (1) the chip select line
174 static void cdns_spi_chipselect(struct spi_device *spi, bool is_high)
176 struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
179 ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET);
182 /* Deselect the slave */
183 ctrl_reg |= CDNS_SPI_CR_SSCTRL_MASK;
185 /* Select the slave */
186 ctrl_reg &= ~CDNS_SPI_CR_SSCTRL_MASK;
187 if (!(xspi->is_decoded_cs))
188 ctrl_reg |= ((~(CDNS_SPI_SS0 << spi->chip_select)) <<
190 CDNS_SPI_CR_SSCTRL_MASK;
192 ctrl_reg |= (spi->chip_select << CDNS_SPI_SS_SHIFT) &
193 CDNS_SPI_CR_SSCTRL_MASK;
196 cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, ctrl_reg);
200 * cdns_spi_config_clock_mode - Sets clock polarity and phase
201 * @spi: Pointer to the spi_device structure
203 * Sets the requested clock polarity and phase.
205 static void cdns_spi_config_clock_mode(struct spi_device *spi)
207 struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
208 u32 ctrl_reg, new_ctrl_reg;
210 new_ctrl_reg = ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET);
212 /* Set the SPI clock phase and clock polarity */
213 new_ctrl_reg &= ~(CDNS_SPI_CR_CPHA_MASK | CDNS_SPI_CR_CPOL_MASK);
214 if (spi->mode & SPI_CPHA)
215 new_ctrl_reg |= CDNS_SPI_CR_CPHA_MASK;
216 if (spi->mode & SPI_CPOL)
217 new_ctrl_reg |= CDNS_SPI_CR_CPOL_MASK;
219 if (new_ctrl_reg != ctrl_reg) {
221 * Just writing the CR register does not seem to apply the clock
222 * setting changes. This is problematic when changing the clock
223 * polarity as it will cause the SPI slave to see spurious clock
224 * transitions. To workaround the issue toggle the ER register.
226 cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
227 CDNS_SPI_ER_DISABLE_MASK);
228 cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, new_ctrl_reg);
229 cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
230 CDNS_SPI_ER_ENABLE_MASK);
235 * cdns_spi_config_clock_freq - Sets clock frequency
236 * @spi: Pointer to the spi_device structure
237 * @transfer: Pointer to the spi_transfer structure which provides
238 * information about next transfer setup parameters
240 * Sets the requested clock frequency.
241 * Note: If the requested frequency is not an exact match with what can be
242 * obtained using the prescalar value the driver sets the clock frequency which
243 * is lower than the requested frequency (maximum lower) for the transfer. If
244 * the requested frequency is higher or lower than that is supported by the SPI
245 * controller the driver will set the highest or lowest frequency supported by
248 static void cdns_spi_config_clock_freq(struct spi_device *spi,
249 struct spi_transfer *transfer)
251 struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
252 u32 ctrl_reg, baud_rate_val;
253 unsigned long frequency;
255 frequency = clk_get_rate(xspi->ref_clk);
257 ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET);
259 /* Set the clock frequency */
260 if (xspi->speed_hz != transfer->speed_hz) {
261 /* first valid value is 1 */
262 baud_rate_val = CDNS_SPI_BAUD_DIV_MIN;
263 while ((baud_rate_val < CDNS_SPI_BAUD_DIV_MAX) &&
264 (frequency / (2 << baud_rate_val)) > transfer->speed_hz)
267 ctrl_reg &= ~CDNS_SPI_CR_BAUD_DIV_MASK;
268 ctrl_reg |= baud_rate_val << CDNS_SPI_BAUD_DIV_SHIFT;
270 xspi->speed_hz = frequency / (2 << baud_rate_val);
272 cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, ctrl_reg);
276 * cdns_spi_setup_transfer - Configure SPI controller for specified transfer
277 * @spi: Pointer to the spi_device structure
278 * @transfer: Pointer to the spi_transfer structure which provides
279 * information about next transfer setup parameters
281 * Sets the operational mode of SPI controller for the next SPI transfer and
282 * sets the requested clock frequency.
286 static int cdns_spi_setup_transfer(struct spi_device *spi,
287 struct spi_transfer *transfer)
289 struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
291 cdns_spi_config_clock_freq(spi, transfer);
293 dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u clock speed\n",
294 __func__, spi->mode, spi->bits_per_word,
301 * cdns_spi_fill_tx_fifo - Fills the TX FIFO with as many bytes as possible
302 * @xspi: Pointer to the cdns_spi structure
304 static void cdns_spi_fill_tx_fifo(struct cdns_spi *xspi)
306 unsigned long trans_cnt = 0;
308 while ((trans_cnt < CDNS_SPI_FIFO_DEPTH) &&
309 (xspi->tx_bytes > 0)) {
311 cdns_spi_write(xspi, CDNS_SPI_TXD_OFFSET,
314 cdns_spi_write(xspi, CDNS_SPI_TXD_OFFSET, 0);
322 * cdns_spi_irq - Interrupt service routine of the SPI controller
324 * @dev_id: Pointer to the xspi structure
326 * This function handles TX empty and Mode Fault interrupts only.
327 * On TX empty interrupt this function reads the received data from RX FIFO and
328 * fills the TX FIFO if there is any data remaining to be transferred.
329 * On Mode Fault interrupt this function indicates that transfer is completed,
330 * the SPI subsystem will identify the error as the remaining bytes to be
331 * transferred is non-zero.
333 * Return: IRQ_HANDLED when handled; IRQ_NONE otherwise.
335 static irqreturn_t cdns_spi_irq(int irq, void *dev_id)
337 struct spi_master *master = dev_id;
338 struct cdns_spi *xspi = spi_master_get_devdata(master);
339 u32 intr_status, status;
342 intr_status = cdns_spi_read(xspi, CDNS_SPI_ISR_OFFSET);
343 cdns_spi_write(xspi, CDNS_SPI_ISR_OFFSET, intr_status);
345 if (intr_status & CDNS_SPI_IXR_MODF_MASK) {
346 /* Indicate that transfer is completed, the SPI subsystem will
347 * identify the error as the remaining bytes to be
348 * transferred is non-zero
350 cdns_spi_write(xspi, CDNS_SPI_IDR_OFFSET,
351 CDNS_SPI_IXR_DEFAULT_MASK);
352 spi_finalize_current_transfer(master);
353 status = IRQ_HANDLED;
354 } else if (intr_status & CDNS_SPI_IXR_TXOW_MASK) {
355 unsigned long trans_cnt;
357 trans_cnt = xspi->rx_bytes - xspi->tx_bytes;
359 /* Read out the data from the RX FIFO */
363 data = cdns_spi_read(xspi, CDNS_SPI_RXD_OFFSET);
365 *xspi->rxbuf++ = data;
371 if (xspi->tx_bytes) {
372 /* There is more data to send */
373 cdns_spi_fill_tx_fifo(xspi);
375 /* Transfer is completed */
376 cdns_spi_write(xspi, CDNS_SPI_IDR_OFFSET,
377 CDNS_SPI_IXR_DEFAULT_MASK);
378 spi_finalize_current_transfer(master);
380 status = IRQ_HANDLED;
385 static int cdns_prepare_message(struct spi_master *master,
386 struct spi_message *msg)
388 cdns_spi_config_clock_mode(msg->spi);
393 * cdns_transfer_one - Initiates the SPI transfer
394 * @master: Pointer to spi_master structure
395 * @spi: Pointer to the spi_device structure
396 * @transfer: Pointer to the spi_transfer structure which provides
397 * information about next transfer parameters
399 * This function fills the TX FIFO, starts the SPI transfer and
400 * returns a positive transfer count so that core will wait for completion.
402 * Return: Number of bytes transferred in the last transfer
404 static int cdns_transfer_one(struct spi_master *master,
405 struct spi_device *spi,
406 struct spi_transfer *transfer)
408 struct cdns_spi *xspi = spi_master_get_devdata(master);
410 xspi->txbuf = transfer->tx_buf;
411 xspi->rxbuf = transfer->rx_buf;
412 xspi->tx_bytes = transfer->len;
413 xspi->rx_bytes = transfer->len;
415 cdns_spi_setup_transfer(spi, transfer);
417 cdns_spi_fill_tx_fifo(xspi);
419 cdns_spi_write(xspi, CDNS_SPI_IER_OFFSET,
420 CDNS_SPI_IXR_DEFAULT_MASK);
421 return transfer->len;
425 * cdns_prepare_transfer_hardware - Prepares hardware for transfer.
426 * @master: Pointer to the spi_master structure which provides
427 * information about the controller.
429 * This function enables SPI master controller.
433 static int cdns_prepare_transfer_hardware(struct spi_master *master)
435 struct cdns_spi *xspi = spi_master_get_devdata(master);
437 cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
438 CDNS_SPI_ER_ENABLE_MASK);
444 * cdns_unprepare_transfer_hardware - Relaxes hardware after transfer
445 * @master: Pointer to the spi_master structure which provides
446 * information about the controller.
448 * This function disables the SPI master controller.
452 static int cdns_unprepare_transfer_hardware(struct spi_master *master)
454 struct cdns_spi *xspi = spi_master_get_devdata(master);
456 cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
457 CDNS_SPI_ER_DISABLE_MASK);
463 * cdns_spi_probe - Probe method for the SPI driver
464 * @pdev: Pointer to the platform_device structure
466 * This function initializes the driver data structures and the hardware.
468 * Return: 0 on success and error value on error
470 static int cdns_spi_probe(struct platform_device *pdev)
473 struct spi_master *master;
474 struct cdns_spi *xspi;
475 struct resource *res;
478 master = spi_alloc_master(&pdev->dev, sizeof(*xspi));
482 xspi = spi_master_get_devdata(master);
483 master->dev.of_node = pdev->dev.of_node;
484 platform_set_drvdata(pdev, master);
486 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
487 xspi->regs = devm_ioremap_resource(&pdev->dev, res);
488 if (IS_ERR(xspi->regs)) {
489 ret = PTR_ERR(xspi->regs);
493 xspi->pclk = devm_clk_get(&pdev->dev, "pclk");
494 if (IS_ERR(xspi->pclk)) {
495 dev_err(&pdev->dev, "pclk clock not found.\n");
496 ret = PTR_ERR(xspi->pclk);
500 xspi->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
501 if (IS_ERR(xspi->ref_clk)) {
502 dev_err(&pdev->dev, "ref_clk clock not found.\n");
503 ret = PTR_ERR(xspi->ref_clk);
507 ret = clk_prepare_enable(xspi->pclk);
509 dev_err(&pdev->dev, "Unable to enable APB clock.\n");
513 ret = clk_prepare_enable(xspi->ref_clk);
515 dev_err(&pdev->dev, "Unable to enable device clock.\n");
519 /* SPI controller initializations */
520 cdns_spi_init_hw(xspi);
522 irq = platform_get_irq(pdev, 0);
525 dev_err(&pdev->dev, "irq number is invalid\n");
529 ret = devm_request_irq(&pdev->dev, irq, cdns_spi_irq,
530 0, pdev->name, master);
533 dev_err(&pdev->dev, "request_irq failed\n");
537 ret = of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs);
540 master->num_chipselect = CDNS_SPI_DEFAULT_NUM_CS;
542 master->num_chipselect = num_cs;
544 ret = of_property_read_u32(pdev->dev.of_node, "is-decoded-cs",
545 &xspi->is_decoded_cs);
548 xspi->is_decoded_cs = 0;
550 master->prepare_transfer_hardware = cdns_prepare_transfer_hardware;
551 master->prepare_message = cdns_prepare_message;
552 master->transfer_one = cdns_transfer_one;
553 master->unprepare_transfer_hardware = cdns_unprepare_transfer_hardware;
554 master->set_cs = cdns_spi_chipselect;
555 master->mode_bits = SPI_CPOL | SPI_CPHA;
557 /* Set to default valid value */
558 master->max_speed_hz = clk_get_rate(xspi->ref_clk) / 4;
559 xspi->speed_hz = master->max_speed_hz;
561 master->bits_per_word_mask = SPI_BPW_MASK(8);
563 ret = spi_register_master(master);
565 dev_err(&pdev->dev, "spi_register_master failed\n");
572 clk_disable_unprepare(xspi->ref_clk);
574 clk_disable_unprepare(xspi->pclk);
576 spi_master_put(master);
581 * cdns_spi_remove - Remove method for the SPI driver
582 * @pdev: Pointer to the platform_device structure
584 * This function is called if a device is physically removed from the system or
585 * if the driver module is being unloaded. It frees all resources allocated to
588 * Return: 0 on success and error value on error
590 static int cdns_spi_remove(struct platform_device *pdev)
592 struct spi_master *master = platform_get_drvdata(pdev);
593 struct cdns_spi *xspi = spi_master_get_devdata(master);
595 cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
596 CDNS_SPI_ER_DISABLE_MASK);
598 clk_disable_unprepare(xspi->ref_clk);
599 clk_disable_unprepare(xspi->pclk);
601 spi_unregister_master(master);
607 * cdns_spi_suspend - Suspend method for the SPI driver
608 * @dev: Address of the platform_device structure
610 * This function disables the SPI controller and
611 * changes the driver state to "suspend"
615 static int __maybe_unused cdns_spi_suspend(struct device *dev)
617 struct platform_device *pdev = container_of(dev,
618 struct platform_device, dev);
619 struct spi_master *master = platform_get_drvdata(pdev);
620 struct cdns_spi *xspi = spi_master_get_devdata(master);
622 spi_master_suspend(master);
624 clk_disable_unprepare(xspi->ref_clk);
626 clk_disable_unprepare(xspi->pclk);
632 * cdns_spi_resume - Resume method for the SPI driver
633 * @dev: Address of the platform_device structure
635 * This function changes the driver state to "ready"
637 * Return: 0 on success and error value on error
639 static int __maybe_unused cdns_spi_resume(struct device *dev)
641 struct platform_device *pdev = container_of(dev,
642 struct platform_device, dev);
643 struct spi_master *master = platform_get_drvdata(pdev);
644 struct cdns_spi *xspi = spi_master_get_devdata(master);
647 ret = clk_prepare_enable(xspi->pclk);
649 dev_err(dev, "Cannot enable APB clock.\n");
653 ret = clk_prepare_enable(xspi->ref_clk);
655 dev_err(dev, "Cannot enable device clock.\n");
656 clk_disable(xspi->pclk);
659 spi_master_resume(master);
664 static SIMPLE_DEV_PM_OPS(cdns_spi_dev_pm_ops, cdns_spi_suspend,
667 static const struct of_device_id cdns_spi_of_match[] = {
668 { .compatible = "xlnx,zynq-spi-r1p6" },
669 { .compatible = "cdns,spi-r1p6" },
670 { /* end of table */ }
672 MODULE_DEVICE_TABLE(of, cdns_spi_of_match);
674 /* cdns_spi_driver - This structure defines the SPI subsystem platform driver */
675 static struct platform_driver cdns_spi_driver = {
676 .probe = cdns_spi_probe,
677 .remove = cdns_spi_remove,
679 .name = CDNS_SPI_NAME,
680 .of_match_table = cdns_spi_of_match,
681 .pm = &cdns_spi_dev_pm_ops,
685 module_platform_driver(cdns_spi_driver);
687 MODULE_AUTHOR("Xilinx, Inc.");
688 MODULE_DESCRIPTION("Cadence SPI driver");
689 MODULE_LICENSE("GPL");