1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *  CLPS711X SPI bus driver
  4 *
  5 *  Copyright (C) 2012-2016 Alexander Shiyan <shc_work@mail.ru>
  6 */
  7
  8#include <linux/io.h>
  9#include <linux/clk.h>
 10#include <linux/gpio/consumer.h>
 11#include <linux/module.h>
 12#include <linux/interrupt.h>
 13#include <linux/platform_device.h>
 14#include <linux/regmap.h>
 15#include <linux/mfd/syscon.h>
 16#include <linux/mfd/syscon/clps711x.h>
 17#include <linux/spi/spi.h>
 18
 19#define DRIVER_NAME		"clps711x-spi"
 20
 21#define SYNCIO_FRMLEN(x)	((x) << 8)
 22#define SYNCIO_TXFRMEN		(1 << 14)
 23
 24struct spi_clps711x_data {
 25	void __iomem		*syncio;
 26	struct regmap		*syscon;
 27	struct clk		*spi_clk;
 28
 29	u8			*tx_buf;
 30	u8			*rx_buf;
 31	unsigned int		bpw;
 32	int			len;
 33};
 34
 35static int spi_clps711x_prepare_message(struct spi_master *master,
 36					struct spi_message *msg)
 37{
 38	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 39	struct spi_device *spi = msg->spi;
 40
 41	/* Setup mode for transfer */
 42	return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
 43				  (spi->mode & SPI_CPHA) ?
 44				  SYSCON3_ADCCKNSEN : 0);
 45}
 46
 47static int spi_clps711x_transfer_one(struct spi_master *master,
 48				     struct spi_device *spi,
 49				     struct spi_transfer *xfer)
 50{
 51	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 52	u8 data;
 53
 54	clk_set_rate(hw->spi_clk, xfer->speed_hz ? : spi->max_speed_hz);
 55
 56	hw->len = xfer->len;
 57	hw->bpw = xfer->bits_per_word;
 58	hw->tx_buf = (u8 *)xfer->tx_buf;
 59	hw->rx_buf = (u8 *)xfer->rx_buf;
 60
 61	/* Initiate transfer */
 62	data = hw->tx_buf ? *hw->tx_buf++ : 0;
 63	writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
 64
 65	return 1;
 66}
 67
 68static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
 69{
 70	struct spi_master *master = dev_id;
 71	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 72	u8 data;
 73
 74	/* Handle RX */
 75	data = readb(hw->syncio);
 76	if (hw->rx_buf)
 77		*hw->rx_buf++ = data;
 78
 79	/* Handle TX */
 80	if (--hw->len > 0) {
 81		data = hw->tx_buf ? *hw->tx_buf++ : 0;
 82		writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
 83		       hw->syncio);
 84	} else
 85		spi_finalize_current_transfer(master);
 86
 87	return IRQ_HANDLED;
 88}
 89
 90static int spi_clps711x_probe(struct platform_device *pdev)
 91{
 92	struct spi_clps711x_data *hw;
 93	struct spi_master *master;
 94	int irq, ret;
 95
 96	irq = platform_get_irq(pdev, 0);
 97	if (irq < 0)
 98		return irq;
 99
100	master = spi_alloc_master(&pdev->dev, sizeof(*hw));
101	if (!master)
102		return -ENOMEM;
103
104	master->use_gpio_descriptors = true;
105	master->bus_num = -1;
106	master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
107	master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
108	master->dev.of_node = pdev->dev.of_node;
109	master->prepare_message = spi_clps711x_prepare_message;
110	master->transfer_one = spi_clps711x_transfer_one;
111
112	hw = spi_master_get_devdata(master);
113
114	hw->spi_clk = devm_clk_get(&pdev->dev, NULL);
115	if (IS_ERR(hw->spi_clk)) {
116		ret = PTR_ERR(hw->spi_clk);
117		goto err_out;
118	}
119
120	hw->syscon =
121		syscon_regmap_lookup_by_compatible("cirrus,ep7209-syscon3");
122	if (IS_ERR(hw->syscon)) {
123		ret = PTR_ERR(hw->syscon);
124		goto err_out;
125	}
126
127	hw->syncio = devm_platform_ioremap_resource(pdev, 0);
128	if (IS_ERR(hw->syncio)) {
129		ret = PTR_ERR(hw->syncio);
130		goto err_out;
131	}
132
133	/* Disable extended mode due hardware problems */
134	regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
135
136	/* Clear possible pending interrupt */
137	readl(hw->syncio);
138
139	ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
140			       dev_name(&pdev->dev), master);
141	if (ret)
142		goto err_out;
143
144	ret = devm_spi_register_master(&pdev->dev, master);
145	if (!ret)
146		return 0;
147
148err_out:
149	spi_master_put(master);
150
151	return ret;
152}
153
154static const struct of_device_id clps711x_spi_dt_ids[] = {
155	{ .compatible = "cirrus,ep7209-spi", },
156	{ }
157};
158MODULE_DEVICE_TABLE(of, clps711x_spi_dt_ids);
159
160static struct platform_driver clps711x_spi_driver = {
161	.driver	= {
162		.name	= DRIVER_NAME,
163		.of_match_table = clps711x_spi_dt_ids,
164	},
165	.probe	= spi_clps711x_probe,
166};
167module_platform_driver(clps711x_spi_driver);
168
169MODULE_LICENSE("GPL");
170MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
171MODULE_DESCRIPTION("CLPS711X SPI bus driver");
172MODULE_ALIAS("platform:" DRIVER_NAME);