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Linux/drivers/spi/spi-clps711x.c

  1 /*
  2  *  CLPS711X SPI bus driver
  3  *
  4  *  Copyright (C) 2012-2014 Alexander Shiyan <shc_work@mail.ru>
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  */
 11 
 12 #include <linux/io.h>
 13 #include <linux/clk.h>
 14 #include <linux/gpio.h>
 15 #include <linux/delay.h>
 16 #include <linux/module.h>
 17 #include <linux/interrupt.h>
 18 #include <linux/platform_device.h>
 19 #include <linux/regmap.h>
 20 #include <linux/mfd/syscon.h>
 21 #include <linux/mfd/syscon/clps711x.h>
 22 #include <linux/spi/spi.h>
 23 #include <linux/platform_data/spi-clps711x.h>
 24 
 25 #define DRIVER_NAME     "spi-clps711x"
 26 
 27 #define SYNCIO_FRMLEN(x)        ((x) << 8)
 28 #define SYNCIO_TXFRMEN          (1 << 14)
 29 
 30 struct spi_clps711x_data {
 31         void __iomem            *syncio;
 32         struct regmap           *syscon;
 33         struct regmap           *syscon1;
 34         struct clk              *spi_clk;
 35 
 36         u8                      *tx_buf;
 37         u8                      *rx_buf;
 38         unsigned int            bpw;
 39         int                     len;
 40 };
 41 
 42 static int spi_clps711x_setup(struct spi_device *spi)
 43 {
 44         /* We are expect that SPI-device is not selected */
 45         gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
 46 
 47         return 0;
 48 }
 49 
 50 static void spi_clps711x_setup_xfer(struct spi_device *spi,
 51                                     struct spi_transfer *xfer)
 52 {
 53         struct spi_master *master = spi->master;
 54         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 55 
 56         /* Setup SPI frequency divider */
 57         if (xfer->speed_hz >= master->max_speed_hz)
 58                 regmap_update_bits(hw->syscon1, SYSCON_OFFSET,
 59                                    SYSCON1_ADCKSEL_MASK, SYSCON1_ADCKSEL(3));
 60         else if (xfer->speed_hz >= (master->max_speed_hz / 2))
 61                 regmap_update_bits(hw->syscon1, SYSCON_OFFSET,
 62                                    SYSCON1_ADCKSEL_MASK, SYSCON1_ADCKSEL(2));
 63         else if (xfer->speed_hz >= (master->max_speed_hz / 8))
 64                 regmap_update_bits(hw->syscon1, SYSCON_OFFSET,
 65                                    SYSCON1_ADCKSEL_MASK, SYSCON1_ADCKSEL(1));
 66         else
 67                 regmap_update_bits(hw->syscon1, SYSCON_OFFSET,
 68                                    SYSCON1_ADCKSEL_MASK, SYSCON1_ADCKSEL(0));
 69 }
 70 
 71 static int spi_clps711x_prepare_message(struct spi_master *master,
 72                                         struct spi_message *msg)
 73 {
 74         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 75         struct spi_device *spi = msg->spi;
 76 
 77         /* Setup mode for transfer */
 78         return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
 79                                   (spi->mode & SPI_CPHA) ?
 80                                   SYSCON3_ADCCKNSEN : 0);
 81 }
 82 
 83 static int spi_clps711x_transfer_one(struct spi_master *master,
 84                                      struct spi_device *spi,
 85                                      struct spi_transfer *xfer)
 86 {
 87         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 88         u8 data;
 89 
 90         spi_clps711x_setup_xfer(spi, xfer);
 91 
 92         hw->len = xfer->len;
 93         hw->bpw = xfer->bits_per_word;
 94         hw->tx_buf = (u8 *)xfer->tx_buf;
 95         hw->rx_buf = (u8 *)xfer->rx_buf;
 96 
 97         /* Initiate transfer */
 98         data = hw->tx_buf ? *hw->tx_buf++ : 0;
 99         writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
100 
101         return 1;
102 }
103 
104 static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
105 {
106         struct spi_master *master = dev_id;
107         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
108         u8 data;
109 
110         /* Handle RX */
111         data = readb(hw->syncio);
112         if (hw->rx_buf)
113                 *hw->rx_buf++ = data;
114 
115         /* Handle TX */
116         if (--hw->len > 0) {
117                 data = hw->tx_buf ? *hw->tx_buf++ : 0;
118                 writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
119                        hw->syncio);
120         } else
121                 spi_finalize_current_transfer(master);
122 
123         return IRQ_HANDLED;
124 }
125 
126 static int spi_clps711x_probe(struct platform_device *pdev)
127 {
128         struct spi_clps711x_data *hw;
129         struct spi_clps711x_pdata *pdata = dev_get_platdata(&pdev->dev);
130         struct spi_master *master;
131         struct resource *res;
132         int i, irq, ret;
133 
134         if (!pdata) {
135                 dev_err(&pdev->dev, "No platform data supplied\n");
136                 return -EINVAL;
137         }
138 
139         if (pdata->num_chipselect < 1) {
140                 dev_err(&pdev->dev, "At least one CS must be defined\n");
141                 return -EINVAL;
142         }
143 
144         irq = platform_get_irq(pdev, 0);
145         if (irq < 0)
146                 return irq;
147 
148         master = spi_alloc_master(&pdev->dev, sizeof(*hw));
149         if (!master)
150                 return -ENOMEM;
151 
152         master->cs_gpios = devm_kzalloc(&pdev->dev, sizeof(int) *
153                                         pdata->num_chipselect, GFP_KERNEL);
154         if (!master->cs_gpios) {
155                 ret = -ENOMEM;
156                 goto err_out;
157         }
158 
159         master->bus_num = pdev->id;
160         master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
161         master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
162         master->num_chipselect = pdata->num_chipselect;
163         master->setup = spi_clps711x_setup;
164         master->prepare_message = spi_clps711x_prepare_message;
165         master->transfer_one = spi_clps711x_transfer_one;
166 
167         hw = spi_master_get_devdata(master);
168 
169         for (i = 0; i < master->num_chipselect; i++) {
170                 master->cs_gpios[i] = pdata->chipselect[i];
171                 ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
172                                         DRIVER_NAME);
173                 if (ret) {
174                         dev_err(&pdev->dev, "Can't get CS GPIO %i\n", i);
175                         goto err_out;
176                 }
177         }
178 
179         hw->spi_clk = devm_clk_get(&pdev->dev, "spi");
180         if (IS_ERR(hw->spi_clk)) {
181                 dev_err(&pdev->dev, "Can't get clocks\n");
182                 ret = PTR_ERR(hw->spi_clk);
183                 goto err_out;
184         }
185         master->max_speed_hz = clk_get_rate(hw->spi_clk);
186 
187         platform_set_drvdata(pdev, master);
188 
189         hw->syscon = syscon_regmap_lookup_by_pdevname("syscon.3");
190         if (IS_ERR(hw->syscon)) {
191                 ret = PTR_ERR(hw->syscon);
192                 goto err_out;
193         }
194 
195         hw->syscon1 = syscon_regmap_lookup_by_pdevname("syscon.1");
196         if (IS_ERR(hw->syscon1)) {
197                 ret = PTR_ERR(hw->syscon1);
198                 goto err_out;
199         }
200 
201         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
202         hw->syncio = devm_ioremap_resource(&pdev->dev, res);
203         if (IS_ERR(hw->syncio)) {
204                 ret = PTR_ERR(hw->syncio);
205                 goto err_out;
206         }
207 
208         /* Disable extended mode due hardware problems */
209         regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
210 
211         /* Clear possible pending interrupt */
212         readl(hw->syncio);
213 
214         ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
215                                dev_name(&pdev->dev), master);
216         if (ret)
217                 goto err_out;
218 
219         ret = devm_spi_register_master(&pdev->dev, master);
220         if (!ret) {
221                 dev_info(&pdev->dev,
222                          "SPI bus driver initialized. Master clock %u Hz\n",
223                          master->max_speed_hz);
224                 return 0;
225         }
226 
227         dev_err(&pdev->dev, "Failed to register master\n");
228 
229 err_out:
230         spi_master_put(master);
231 
232         return ret;
233 }
234 
235 static struct platform_driver clps711x_spi_driver = {
236         .driver = {
237                 .name   = DRIVER_NAME,
238                 .owner  = THIS_MODULE,
239         },
240         .probe  = spi_clps711x_probe,
241 };
242 module_platform_driver(clps711x_spi_driver);
243 
244 MODULE_LICENSE("GPL");
245 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
246 MODULE_DESCRIPTION("CLPS711X SPI bus driver");
247 MODULE_ALIAS("platform:" DRIVER_NAME);
248 

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