drivers/iio/adc/stm32-dfsdm-core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * This file is part the core part STM32 DFSDM driver
   4  *
   5  * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
   6  * Author(s): Arnaud Pouliquen <arnaud.pouliquen@st.com> for STMicroelectronics.
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/iio/iio.h>
  11 #include <linux/iio/sysfs.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/module.h>
  14 #include <linux/of_device.h>
  15 #include <linux/regmap.h>
  16 #include <linux/slab.h>
  17
  18 #include "stm32-dfsdm.h"
  19
  20 struct stm32_dfsdm_dev_data {
  21         unsigned int num_filters;
  22         unsigned int num_channels;
  23         const struct regmap_config *regmap_cfg;
  24 };
  25
  26 #define STM32H7_DFSDM_NUM_FILTERS       4
  27 #define STM32H7_DFSDM_NUM_CHANNELS      8
  28 #define STM32MP1_DFSDM_NUM_FILTERS      6
  29 #define STM32MP1_DFSDM_NUM_CHANNELS     8
  30
  31 static bool stm32_dfsdm_volatile_reg(struct device *dev, unsigned int reg)
  32 {
  33         if (reg < DFSDM_FILTER_BASE_ADR)
  34                 return false;
  35
  36         /*
  37          * Mask is done on register to avoid to list registers of all
  38          * filter instances.
  39          */
  40         switch (reg & DFSDM_FILTER_REG_MASK) {
  41         case DFSDM_CR1(0) & DFSDM_FILTER_REG_MASK:
  42         case DFSDM_ISR(0) & DFSDM_FILTER_REG_MASK:
  43         case DFSDM_JDATAR(0) & DFSDM_FILTER_REG_MASK:
  44         case DFSDM_RDATAR(0) & DFSDM_FILTER_REG_MASK:
  45                 return true;
  46         }
  47
  48         return false;
  49 }
  50
  51 static const struct regmap_config stm32h7_dfsdm_regmap_cfg = {
  52         .reg_bits = 32,
  53         .val_bits = 32,
  54         .reg_stride = sizeof(u32),
  55         .max_register = 0x2B8,
  56         .volatile_reg = stm32_dfsdm_volatile_reg,
  57         .fast_io = true,
  58 };
  59
  60 static const struct stm32_dfsdm_dev_data stm32h7_dfsdm_data = {
  61         .num_filters = STM32H7_DFSDM_NUM_FILTERS,
  62         .num_channels = STM32H7_DFSDM_NUM_CHANNELS,
  63         .regmap_cfg = &stm32h7_dfsdm_regmap_cfg,
  64 };
  65
  66 static const struct regmap_config stm32mp1_dfsdm_regmap_cfg = {
  67         .reg_bits = 32,
  68         .val_bits = 32,
  69         .reg_stride = sizeof(u32),
  70         .max_register = 0x7fc,
  71         .volatile_reg = stm32_dfsdm_volatile_reg,
  72         .fast_io = true,
  73 };
  74
  75 static const struct stm32_dfsdm_dev_data stm32mp1_dfsdm_data = {
  76         .num_filters = STM32MP1_DFSDM_NUM_FILTERS,
  77         .num_channels = STM32MP1_DFSDM_NUM_CHANNELS,
  78         .regmap_cfg = &stm32mp1_dfsdm_regmap_cfg,
  79 };
  80
  81 struct dfsdm_priv {
  82         struct platform_device *pdev; /* platform device */
  83
  84         struct stm32_dfsdm dfsdm; /* common data exported for all instances */
  85
  86         unsigned int spi_clk_out_div; /* SPI clkout divider value */
  87         atomic_t n_active_ch;   /* number of current active channels */
  88
  89         struct clk *clk; /* DFSDM clock */
  90         struct clk *aclk; /* audio clock */
  91 };
  92
  93 /**
  94  * stm32_dfsdm_start_dfsdm - start global dfsdm interface.
  95  *
  96  * Enable interface if n_active_ch is not null.
  97  * @dfsdm: Handle used to retrieve dfsdm context.
  98  */
  99 int stm32_dfsdm_start_dfsdm(struct stm32_dfsdm *dfsdm)
 100 {
 101         struct dfsdm_priv *priv = container_of(dfsdm, struct dfsdm_priv, dfsdm);
 102         struct device *dev = &priv->pdev->dev;
 103         unsigned int clk_div = priv->spi_clk_out_div, clk_src;
 104         int ret;
 105
 106         if (atomic_inc_return(&priv->n_active_ch) == 1) {
 107                 ret = clk_prepare_enable(priv->clk);
 108                 if (ret < 0) {
 109                         dev_err(dev, "Failed to start clock\n");
 110                         goto error_ret;
 111                 }
 112                 if (priv->aclk) {
 113                         ret = clk_prepare_enable(priv->aclk);
 114                         if (ret < 0) {
 115                                 dev_err(dev, "Failed to start audio clock\n");
 116                                 goto disable_clk;
 117                         }
 118                 }
 119
 120                 /* select clock source, e.g. 0 for "dfsdm" or 1 for "audio" */
 121                 clk_src = priv->aclk ? 1 : 0;
 122                 ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
 123                                          DFSDM_CHCFGR1_CKOUTSRC_MASK,
 124                                          DFSDM_CHCFGR1_CKOUTSRC(clk_src));
 125                 if (ret < 0)
 126                         goto disable_aclk;
 127
 128                 /* Output the SPI CLKOUT (if clk_div == 0 clock if OFF) */
 129                 ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
 130                                          DFSDM_CHCFGR1_CKOUTDIV_MASK,
 131                                          DFSDM_CHCFGR1_CKOUTDIV(clk_div));
 132                 if (ret < 0)
 133                         goto disable_aclk;
 134
 135                 /* Global enable of DFSDM interface */
 136                 ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
 137                                          DFSDM_CHCFGR1_DFSDMEN_MASK,
 138                                          DFSDM_CHCFGR1_DFSDMEN(1));
 139                 if (ret < 0)
 140                         goto disable_aclk;
 141         }
 142
 143         dev_dbg(dev, "%s: n_active_ch %d\n", __func__,
 144                 atomic_read(&priv->n_active_ch));
 145
 146         return 0;
 147
 148 disable_aclk:
 149         clk_disable_unprepare(priv->aclk);
 150 disable_clk:
 151         clk_disable_unprepare(priv->clk);
 152
 153 error_ret:
 154         atomic_dec(&priv->n_active_ch);
 155
 156         return ret;
 157 }
 158 EXPORT_SYMBOL_GPL(stm32_dfsdm_start_dfsdm);
 159
 160 /**
 161  * stm32_dfsdm_stop_dfsdm - stop global DFSDM interface.
 162  *
 163  * Disable interface if n_active_ch is null
 164  * @dfsdm: Handle used to retrieve dfsdm context.
 165  */
 166 int stm32_dfsdm_stop_dfsdm(struct stm32_dfsdm *dfsdm)
 167 {
 168         struct dfsdm_priv *priv = container_of(dfsdm, struct dfsdm_priv, dfsdm);
 169         int ret;
 170
 171         if (atomic_dec_and_test(&priv->n_active_ch)) {
 172                 /* Global disable of DFSDM interface */
 173                 ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
 174                                          DFSDM_CHCFGR1_DFSDMEN_MASK,
 175                                          DFSDM_CHCFGR1_DFSDMEN(0));
 176                 if (ret < 0)
 177                         return ret;
 178
 179                 /* Stop SPI CLKOUT */
 180                 ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
 181                                          DFSDM_CHCFGR1_CKOUTDIV_MASK,
 182                                          DFSDM_CHCFGR1_CKOUTDIV(0));
 183                 if (ret < 0)
 184                         return ret;
 185
 186                 clk_disable_unprepare(priv->clk);
 187                 if (priv->aclk)
 188                         clk_disable_unprepare(priv->aclk);
 189         }
 190         dev_dbg(&priv->pdev->dev, "%s: n_active_ch %d\n", __func__,
 191                 atomic_read(&priv->n_active_ch));
 192
 193         return 0;
 194 }
 195 EXPORT_SYMBOL_GPL(stm32_dfsdm_stop_dfsdm);
 196
 197 static int stm32_dfsdm_parse_of(struct platform_device *pdev,
 198                                 struct dfsdm_priv *priv)
 199 {
 200         struct device_node *node = pdev->dev.of_node;
 201         struct resource *res;
 202         unsigned long clk_freq;
 203         unsigned int spi_freq, rem;
 204         int ret;
 205
 206         if (!node)
 207                 return -EINVAL;
 208
 209         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 210         if (!res) {
 211                 dev_err(&pdev->dev, "Failed to get memory resource\n");
 212                 return -ENODEV;
 213         }
 214         priv->dfsdm.phys_base = res->start;
 215         priv->dfsdm.base = devm_ioremap_resource(&pdev->dev, res);
 216
 217         /*
 218          * "dfsdm" clock is mandatory for DFSDM peripheral clocking.
 219          * "dfsdm" or "audio" clocks can be used as source clock for
 220          * the SPI clock out signal and internal processing, depending
 221          * on use case.
 222          */
 223         priv->clk = devm_clk_get(&pdev->dev, "dfsdm");
 224         if (IS_ERR(priv->clk)) {
 225                 dev_err(&pdev->dev, "No stm32_dfsdm_clk clock found\n");
 226                 return -EINVAL;
 227         }
 228
 229         priv->aclk = devm_clk_get(&pdev->dev, "audio");
 230         if (IS_ERR(priv->aclk))
 231                 priv->aclk = NULL;
 232
 233         if (priv->aclk)
 234                 clk_freq = clk_get_rate(priv->aclk);
 235         else
 236                 clk_freq = clk_get_rate(priv->clk);
 237
 238         /* SPI clock out frequency */
 239         ret = of_property_read_u32(pdev->dev.of_node, "spi-max-frequency",
 240                                    &spi_freq);
 241         if (ret < 0) {
 242                 /* No SPI master mode */
 243                 return 0;
 244         }
 245
 246         priv->spi_clk_out_div = div_u64_rem(clk_freq, spi_freq, &rem) - 1;
 247         if (!priv->spi_clk_out_div) {
 248                 /* spi_clk_out_div == 0 means ckout is OFF */
 249                 dev_err(&pdev->dev, "spi-max-frequency not achievable\n");
 250                 return -EINVAL;
 251         }
 252         priv->dfsdm.spi_master_freq = spi_freq;
 253
 254         if (rem) {
 255                 dev_warn(&pdev->dev, "SPI clock not accurate\n");
 256                 dev_warn(&pdev->dev, "%ld = %d * %d + %d\n",
 257                          clk_freq, spi_freq, priv->spi_clk_out_div + 1, rem);
 258         }
 259
 260         return 0;
 261 };
 262
 263 static const struct of_device_id stm32_dfsdm_of_match[] = {
 264         {
 265                 .compatible = "st,stm32h7-dfsdm",
 266                 .data = &stm32h7_dfsdm_data,
 267         },
 268         {
 269                 .compatible = "st,stm32mp1-dfsdm",
 270                 .data = &stm32mp1_dfsdm_data,
 271         },
 272         {}
 273 };
 274 MODULE_DEVICE_TABLE(of, stm32_dfsdm_of_match);
 275
 276 static int stm32_dfsdm_probe(struct platform_device *pdev)
 277 {
 278         struct dfsdm_priv *priv;
 279         const struct stm32_dfsdm_dev_data *dev_data;
 280         struct stm32_dfsdm *dfsdm;
 281         int ret;
 282
 283         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 284         if (!priv)
 285                 return -ENOMEM;
 286
 287         priv->pdev = pdev;
 288
 289         dev_data = of_device_get_match_data(&pdev->dev);
 290
 291         dfsdm = &priv->dfsdm;
 292         dfsdm->fl_list = devm_kcalloc(&pdev->dev, dev_data->num_filters,
 293                                       sizeof(*dfsdm->fl_list), GFP_KERNEL);
 294         if (!dfsdm->fl_list)
 295                 return -ENOMEM;
 296
 297         dfsdm->num_fls = dev_data->num_filters;
 298         dfsdm->ch_list = devm_kcalloc(&pdev->dev, dev_data->num_channels,
 299                                       sizeof(*dfsdm->ch_list),
 300                                       GFP_KERNEL);
 301         if (!dfsdm->ch_list)
 302                 return -ENOMEM;
 303         dfsdm->num_chs = dev_data->num_channels;
 304
 305         ret = stm32_dfsdm_parse_of(pdev, priv);
 306         if (ret < 0)
 307                 return ret;
 308
 309         dfsdm->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "dfsdm",
 310                                                   dfsdm->base,
 311                                                   dev_data->regmap_cfg);
 312         if (IS_ERR(dfsdm->regmap)) {
 313                 ret = PTR_ERR(dfsdm->regmap);
 314                 dev_err(&pdev->dev, "%s: Failed to allocate regmap: %d\n",
 315                         __func__, ret);
 316                 return ret;
 317         }
 318
 319         platform_set_drvdata(pdev, dfsdm);
 320
 321         return devm_of_platform_populate(&pdev->dev);
 322 }
 323
 324 static struct platform_driver stm32_dfsdm_driver = {
 325         .probe = stm32_dfsdm_probe,
 326         .driver = {
 327                 .name = "stm32-dfsdm",
 328                 .of_match_table = stm32_dfsdm_of_match,
 329         },
 330 };
 331
 332 module_platform_driver(stm32_dfsdm_driver);
 333
 334 MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>");
 335 MODULE_DESCRIPTION("STMicroelectronics STM32 dfsdm driver");
 336 MODULE_LICENSE("GPL v2");