drivers/spi/spi-ath79.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs
   4  *
   5  * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
   6  *
   7  * This driver has been based on the spi-gpio.c:
   8  *      Copyright (C) 2006,2008 David Brownell
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/delay.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/io.h>
  17 #include <linux/spi/spi.h>
  18 #include <linux/spi/spi_bitbang.h>
  19 #include <linux/bitops.h>
  20 #include <linux/clk.h>
  21 #include <linux/err.h>
  22 #include <linux/platform_data/spi-ath79.h>
  23
  24 #define DRV_NAME        "ath79-spi"
  25
  26 #define ATH79_SPI_RRW_DELAY_FACTOR      12000
  27 #define MHZ                             (1000 * 1000)
  28
  29 #define AR71XX_SPI_REG_FS               0x00    /* Function Select */
  30 #define AR71XX_SPI_REG_CTRL             0x04    /* SPI Control */
  31 #define AR71XX_SPI_REG_IOC              0x08    /* SPI I/O Control */
  32 #define AR71XX_SPI_REG_RDS              0x0c    /* Read Data Shift */
  33
  34 #define AR71XX_SPI_FS_GPIO              BIT(0)  /* Enable GPIO mode */
  35
  36 #define AR71XX_SPI_IOC_DO               BIT(0)  /* Data Out pin */
  37 #define AR71XX_SPI_IOC_CLK              BIT(8)  /* CLK pin */
  38 #define AR71XX_SPI_IOC_CS(n)            BIT(16 + (n))
  39
  40 struct ath79_spi {
  41         struct spi_bitbang      bitbang;
  42         u32                     ioc_base;
  43         u32                     reg_ctrl;
  44         void __iomem            *base;
  45         struct clk              *clk;
  46         unsigned int            rrw_delay;
  47 };
  48
  49 static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned int reg)
  50 {
  51         return ioread32(sp->base + reg);
  52 }
  53
  54 static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned int reg, u32 val)
  55 {
  56         iowrite32(val, sp->base + reg);
  57 }
  58
  59 static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
  60 {
  61         return spi_master_get_devdata(spi->master);
  62 }
  63
  64 static inline void ath79_spi_delay(struct ath79_spi *sp, unsigned int nsecs)
  65 {
  66         if (nsecs > sp->rrw_delay)
  67                 ndelay(nsecs - sp->rrw_delay);
  68 }
  69
  70 static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
  71 {
  72         struct ath79_spi *sp = ath79_spidev_to_sp(spi);
  73         int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;
  74         u32 cs_bit = AR71XX_SPI_IOC_CS(spi->chip_select);
  75
  76         if (cs_high)
  77                 sp->ioc_base |= cs_bit;
  78         else
  79                 sp->ioc_base &= ~cs_bit;
  80
  81         ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
  82 }
  83
  84 static void ath79_spi_enable(struct ath79_spi *sp)
  85 {
  86         /* enable GPIO mode */
  87         ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
  88
  89         /* save CTRL register */
  90         sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
  91         sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);
  92
  93         /* clear clk and mosi in the base state */
  94         sp->ioc_base &= ~(AR71XX_SPI_IOC_DO | AR71XX_SPI_IOC_CLK);
  95
  96         /* TODO: setup speed? */
  97         ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);
  98 }
  99
 100 static void ath79_spi_disable(struct ath79_spi *sp)
 101 {
 102         /* restore CTRL register */
 103         ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
 104         /* disable GPIO mode */
 105         ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
 106 }
 107
 108 static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned int nsecs,
 109                                u32 word, u8 bits, unsigned flags)
 110 {
 111         struct ath79_spi *sp = ath79_spidev_to_sp(spi);
 112         u32 ioc = sp->ioc_base;
 113
 114         /* clock starts at inactive polarity */
 115         for (word <<= (32 - bits); likely(bits); bits--) {
 116                 u32 out;
 117
 118                 if (word & (1 << 31))
 119                         out = ioc | AR71XX_SPI_IOC_DO;
 120                 else
 121                         out = ioc & ~AR71XX_SPI_IOC_DO;
 122
 123                 /* setup MSB (to slave) on trailing edge */
 124                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
 125                 ath79_spi_delay(sp, nsecs);
 126                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
 127                 ath79_spi_delay(sp, nsecs);
 128                 if (bits == 1)
 129                         ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
 130
 131                 word <<= 1;
 132         }
 133
 134         return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
 135 }
 136
 137 static int ath79_spi_probe(struct platform_device *pdev)
 138 {
 139         struct spi_master *master;
 140         struct ath79_spi *sp;
 141         struct ath79_spi_platform_data *pdata;
 142         unsigned long rate;
 143         int ret;
 144
 145         master = spi_alloc_master(&pdev->dev, sizeof(*sp));
 146         if (master == NULL) {
 147                 dev_err(&pdev->dev, "failed to allocate spi master\n");
 148                 return -ENOMEM;
 149         }
 150
 151         sp = spi_master_get_devdata(master);
 152         master->dev.of_node = pdev->dev.of_node;
 153         platform_set_drvdata(pdev, sp);
 154
 155         pdata = dev_get_platdata(&pdev->dev);
 156
 157         master->use_gpio_descriptors = true;
 158         master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
 159         master->setup = spi_bitbang_setup;
 160         master->cleanup = spi_bitbang_cleanup;
 161         if (pdata) {
 162                 master->bus_num = pdata->bus_num;
 163                 master->num_chipselect = pdata->num_chipselect;
 164         }
 165
 166         sp->bitbang.master = master;
 167         sp->bitbang.chipselect = ath79_spi_chipselect;
 168         sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0;
 169         sp->bitbang.flags = SPI_CS_HIGH;
 170
 171         sp->base = devm_platform_ioremap_resource(pdev, 0);
 172         if (IS_ERR(sp->base)) {
 173                 ret = PTR_ERR(sp->base);
 174                 goto err_put_master;
 175         }
 176
 177         sp->clk = devm_clk_get(&pdev->dev, "ahb");
 178         if (IS_ERR(sp->clk)) {
 179                 ret = PTR_ERR(sp->clk);
 180                 goto err_put_master;
 181         }
 182
 183         ret = clk_prepare_enable(sp->clk);
 184         if (ret)
 185                 goto err_put_master;
 186
 187         rate = DIV_ROUND_UP(clk_get_rate(sp->clk), MHZ);
 188         if (!rate) {
 189                 ret = -EINVAL;
 190                 goto err_clk_disable;
 191         }
 192
 193         sp->rrw_delay = ATH79_SPI_RRW_DELAY_FACTOR / rate;
 194         dev_dbg(&pdev->dev, "register read/write delay is %u nsecs\n",
 195                 sp->rrw_delay);
 196
 197         ath79_spi_enable(sp);
 198         ret = spi_bitbang_start(&sp->bitbang);
 199         if (ret)
 200                 goto err_disable;
 201
 202         return 0;
 203
 204 err_disable:
 205         ath79_spi_disable(sp);
 206 err_clk_disable:
 207         clk_disable_unprepare(sp->clk);
 208 err_put_master:
 209         spi_master_put(sp->bitbang.master);
 210
 211         return ret;
 212 }
 213
 214 static int ath79_spi_remove(struct platform_device *pdev)
 215 {
 216         struct ath79_spi *sp = platform_get_drvdata(pdev);
 217
 218         spi_bitbang_stop(&sp->bitbang);
 219         ath79_spi_disable(sp);
 220         clk_disable_unprepare(sp->clk);
 221         spi_master_put(sp->bitbang.master);
 222
 223         return 0;
 224 }
 225
 226 static void ath79_spi_shutdown(struct platform_device *pdev)
 227 {
 228         ath79_spi_remove(pdev);
 229 }
 230
 231 static const struct of_device_id ath79_spi_of_match[] = {
 232         { .compatible = "qca,ar7100-spi", },
 233         { },
 234 };
 235 MODULE_DEVICE_TABLE(of, ath79_spi_of_match);
 236
 237 static struct platform_driver ath79_spi_driver = {
 238         .probe          = ath79_spi_probe,
 239         .remove         = ath79_spi_remove,
 240         .shutdown       = ath79_spi_shutdown,
 241         .driver         = {
 242                 .name   = DRV_NAME,
 243                 .of_match_table = ath79_spi_of_match,
 244         },
 245 };
 246 module_platform_driver(ath79_spi_driver);
 247
 248 MODULE_DESCRIPTION("SPI controller driver for Atheros AR71XX/AR724X/AR913X");
 249 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 250 MODULE_LICENSE("GPL v2");
 251 MODULE_ALIAS("platform:" DRV_NAME);