drivers/spi/spi-dw-bt1.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 //
   3 // Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
   4 //
   5 // Authors:
   6 //   Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>
   7 //   Serge Semin <Sergey.Semin@baikalelectronics.ru>
   8 //
   9 // Baikal-T1 DW APB SPI and System Boot SPI driver
  10 //
  11
  12 #include <linux/clk.h>
  13 #include <linux/cpumask.h>
  14 #include <linux/err.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/module.h>
  17 #include <linux/mux/consumer.h>
  18 #include <linux/of.h>
  19 #include <linux/of_platform.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/pm_runtime.h>
  22 #include <linux/property.h>
  23 #include <linux/slab.h>
  24 #include <linux/spi/spi-mem.h>
  25 #include <linux/spi/spi.h>
  26
  27 #include "spi-dw.h"
  28
  29 #define BT1_BOOT_DIRMAP         0
  30 #define BT1_BOOT_REGS           1
  31
  32 struct dw_spi_bt1 {
  33         struct dw_spi           dws;
  34         struct clk              *clk;
  35         struct mux_control      *mux;
  36
  37 #ifdef CONFIG_SPI_DW_BT1_DIRMAP
  38         void __iomem            *map;
  39         resource_size_t         map_len;
  40 #endif
  41 };
  42 #define to_dw_spi_bt1(_ctlr) \
  43         container_of(spi_controller_get_devdata(_ctlr), struct dw_spi_bt1, dws)
  44
  45 typedef int (*dw_spi_bt1_init_cb)(struct platform_device *pdev,
  46                                     struct dw_spi_bt1 *dwsbt1);
  47
  48 #ifdef CONFIG_SPI_DW_BT1_DIRMAP
  49
  50 static int dw_spi_bt1_dirmap_create(struct spi_mem_dirmap_desc *desc)
  51 {
  52         struct dw_spi_bt1 *dwsbt1 = to_dw_spi_bt1(desc->mem->spi->controller);
  53
  54         if (!dwsbt1->map ||
  55             !dwsbt1->dws.mem_ops.supports_op(desc->mem, &desc->info.op_tmpl))
  56                 return -EOPNOTSUPP;
  57
  58         /*
  59          * Make sure the requested region doesn't go out of the physically
  60          * mapped flash memory bounds and the operation is read-only.
  61          */
  62         if (desc->info.offset + desc->info.length > dwsbt1->map_len ||
  63             desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
  64                 return -EOPNOTSUPP;
  65
  66         return 0;
  67 }
  68
  69 /*
  70  * Directly mapped SPI memory region is only accessible in the dword chunks.
  71  * That's why we have to create a dedicated read-method to copy data from there
  72  * to the passed buffer.
  73  */
  74 static void dw_spi_bt1_dirmap_copy_from_map(void *to, void __iomem *from, size_t len)
  75 {
  76         size_t shift, chunk;
  77         u32 data;
  78
  79         /*
  80          * We split the copying up into the next three stages: unaligned head,
  81          * aligned body, unaligned tail.
  82          */
  83         shift = (size_t)from & 0x3;
  84         if (shift) {
  85                 chunk = min_t(size_t, 4 - shift, len);
  86                 data = readl_relaxed(from - shift);
  87                 memcpy(to, (char *)&data + shift, chunk);
  88                 from += chunk;
  89                 to += chunk;
  90                 len -= chunk;
  91         }
  92
  93         while (len >= 4) {
  94                 data = readl_relaxed(from);
  95                 memcpy(to, &data, 4);
  96                 from += 4;
  97                 to += 4;
  98                 len -= 4;
  99         }
 100
 101         if (len) {
 102                 data = readl_relaxed(from);
 103                 memcpy(to, &data, len);
 104         }
 105 }
 106
 107 static ssize_t dw_spi_bt1_dirmap_read(struct spi_mem_dirmap_desc *desc,
 108                                       u64 offs, size_t len, void *buf)
 109 {
 110         struct dw_spi_bt1 *dwsbt1 = to_dw_spi_bt1(desc->mem->spi->controller);
 111         struct dw_spi *dws = &dwsbt1->dws;
 112         struct spi_mem *mem = desc->mem;
 113         struct dw_spi_cfg cfg;
 114         int ret;
 115
 116         /*
 117          * Make sure the requested operation length is valid. Truncate the
 118          * length if it's greater than the length of the MMIO region.
 119          */
 120         if (offs >= dwsbt1->map_len || !len)
 121                 return 0;
 122
 123         len = min_t(size_t, len, dwsbt1->map_len - offs);
 124
 125         /* Collect the controller configuration required by the operation */
 126         cfg.tmode = SPI_TMOD_EPROMREAD;
 127         cfg.dfs = 8;
 128         cfg.ndf = 4;
 129         cfg.freq = mem->spi->max_speed_hz;
 130
 131         /* Make sure the corresponding CS is de-asserted on transmission */
 132         dw_spi_set_cs(mem->spi, false);
 133
 134         spi_enable_chip(dws, 0);
 135
 136         dw_spi_update_config(dws, mem->spi, &cfg);
 137
 138         spi_umask_intr(dws, SPI_INT_RXFI);
 139
 140         spi_enable_chip(dws, 1);
 141
 142         /*
 143          * Enable the transparent mode of the System Boot Controller.
 144          * The SPI core IO should have been locked before calling this method
 145          * so noone would be touching the controller' registers during the
 146          * dirmap operation.
 147          */
 148         ret = mux_control_select(dwsbt1->mux, BT1_BOOT_DIRMAP);
 149         if (ret)
 150                 return ret;
 151
 152         dw_spi_bt1_dirmap_copy_from_map(buf, dwsbt1->map + offs, len);
 153
 154         mux_control_deselect(dwsbt1->mux);
 155
 156         dw_spi_set_cs(mem->spi, true);
 157
 158         ret = dw_spi_check_status(dws, true);
 159
 160         return ret ?: len;
 161 }
 162
 163 #endif /* CONFIG_SPI_DW_BT1_DIRMAP */
 164
 165 static int dw_spi_bt1_std_init(struct platform_device *pdev,
 166                                struct dw_spi_bt1 *dwsbt1)
 167 {
 168         struct dw_spi *dws = &dwsbt1->dws;
 169
 170         dws->irq = platform_get_irq(pdev, 0);
 171         if (dws->irq < 0)
 172                 return dws->irq;
 173
 174         dws->num_cs = 4;
 175
 176         /*
 177          * Baikal-T1 Normal SPI Controllers don't always keep up with full SPI
 178          * bus speed especially when it comes to the concurrent access to the
 179          * APB bus resources. Thus we have no choice but to set a constraint on
 180          * the SPI bus frequency for the memory operations which require to
 181          * read/write data as fast as possible.
 182          */
 183         dws->max_mem_freq = 20000000U;
 184
 185         dw_spi_dma_setup_generic(dws);
 186
 187         return 0;
 188 }
 189
 190 static int dw_spi_bt1_sys_init(struct platform_device *pdev,
 191                                struct dw_spi_bt1 *dwsbt1)
 192 {
 193         struct resource *mem __maybe_unused;
 194         struct dw_spi *dws = &dwsbt1->dws;
 195
 196         /*
 197          * Baikal-T1 System Boot Controller is equipped with a mux, which
 198          * switches between the directly mapped SPI flash access mode and
 199          * IO access to the DW APB SSI registers. Note the mux controller
 200          * must be setup to preserve the registers being accessible by default
 201          * (on idle-state).
 202          */
 203         dwsbt1->mux = devm_mux_control_get(&pdev->dev, NULL);
 204         if (IS_ERR(dwsbt1->mux))
 205                 return PTR_ERR(dwsbt1->mux);
 206
 207         /*
 208          * Directly mapped SPI flash memory is a 16MB MMIO region, which can be
 209          * used to access a peripheral memory device just by reading/writing
 210          * data from/to it. Note the system APB bus will stall during each IO
 211          * from/to the dirmap region until the operation is finished. So don't
 212          * use it concurrently with time-critical tasks (like the SPI memory
 213          * operations implemented in the DW APB SSI driver).
 214          */
 215 #ifdef CONFIG_SPI_DW_BT1_DIRMAP
 216         mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 217         if (mem) {
 218                 dwsbt1->map = devm_ioremap_resource(&pdev->dev, mem);
 219                 if (!IS_ERR(dwsbt1->map)) {
 220                         dwsbt1->map_len = resource_size(mem);
 221                         dws->mem_ops.dirmap_create = dw_spi_bt1_dirmap_create;
 222                         dws->mem_ops.dirmap_read = dw_spi_bt1_dirmap_read;
 223                 } else {
 224                         dwsbt1->map = NULL;
 225                 }
 226         }
 227 #endif /* CONFIG_SPI_DW_BT1_DIRMAP */
 228
 229         /*
 230          * There is no IRQ, no DMA and just one CS available on the System Boot
 231          * SPI controller.
 232          */
 233         dws->irq = IRQ_NOTCONNECTED;
 234         dws->num_cs = 1;
 235
 236         /*
 237          * Baikal-T1 System Boot SPI Controller doesn't keep up with the full
 238          * SPI bus speed due to relatively slow APB bus and races for it'
 239          * resources from different CPUs. The situation is worsen by a small
 240          * FIFOs depth (just 8 words). It works better in a single CPU mode
 241          * though, but still tends to be not fast enough at low CPU
 242          * frequencies.
 243          */
 244         if (num_possible_cpus() > 1)
 245                 dws->max_mem_freq = 10000000U;
 246         else
 247                 dws->max_mem_freq = 20000000U;
 248
 249         return 0;
 250 }
 251
 252 static int dw_spi_bt1_probe(struct platform_device *pdev)
 253 {
 254         dw_spi_bt1_init_cb init_func;
 255         struct dw_spi_bt1 *dwsbt1;
 256         struct resource *mem;
 257         struct dw_spi *dws;
 258         int ret;
 259
 260         dwsbt1 = devm_kzalloc(&pdev->dev, sizeof(struct dw_spi_bt1), GFP_KERNEL);
 261         if (!dwsbt1)
 262                 return -ENOMEM;
 263
 264         dws = &dwsbt1->dws;
 265
 266         dws->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);
 267         if (IS_ERR(dws->regs))
 268                 return PTR_ERR(dws->regs);
 269
 270         dws->paddr = mem->start;
 271
 272         dwsbt1->clk = devm_clk_get(&pdev->dev, NULL);
 273         if (IS_ERR(dwsbt1->clk))
 274                 return PTR_ERR(dwsbt1->clk);
 275
 276         ret = clk_prepare_enable(dwsbt1->clk);
 277         if (ret)
 278                 return ret;
 279
 280         dws->bus_num = pdev->id;
 281         dws->reg_io_width = 4;
 282         dws->max_freq = clk_get_rate(dwsbt1->clk);
 283         if (!dws->max_freq) {
 284                 ret = -EINVAL;
 285                 goto err_disable_clk;
 286         }
 287
 288         init_func = device_get_match_data(&pdev->dev);
 289         ret = init_func(pdev, dwsbt1);
 290         if (ret)
 291                 goto err_disable_clk;
 292
 293         pm_runtime_enable(&pdev->dev);
 294
 295         ret = dw_spi_add_host(&pdev->dev, dws);
 296         if (ret)
 297                 goto err_disable_clk;
 298
 299         platform_set_drvdata(pdev, dwsbt1);
 300
 301         return 0;
 302
 303 err_disable_clk:
 304         clk_disable_unprepare(dwsbt1->clk);
 305
 306         return ret;
 307 }
 308
 309 static int dw_spi_bt1_remove(struct platform_device *pdev)
 310 {
 311         struct dw_spi_bt1 *dwsbt1 = platform_get_drvdata(pdev);
 312
 313         dw_spi_remove_host(&dwsbt1->dws);
 314
 315         pm_runtime_disable(&pdev->dev);
 316
 317         clk_disable_unprepare(dwsbt1->clk);
 318
 319         return 0;
 320 }
 321
 322 static const struct of_device_id dw_spi_bt1_of_match[] = {
 323         { .compatible = "baikal,bt1-ssi", .data = dw_spi_bt1_std_init},
 324         { .compatible = "baikal,bt1-sys-ssi", .data = dw_spi_bt1_sys_init},
 325         { }
 326 };
 327 MODULE_DEVICE_TABLE(of, dw_spi_bt1_of_match);
 328
 329 static struct platform_driver dw_spi_bt1_driver = {
 330         .probe  = dw_spi_bt1_probe,
 331         .remove = dw_spi_bt1_remove,
 332         .driver = {
 333                 .name           = "bt1-sys-ssi",
 334                 .of_match_table = dw_spi_bt1_of_match,
 335         },
 336 };
 337 module_platform_driver(dw_spi_bt1_driver);
 338
 339 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
 340 MODULE_DESCRIPTION("Baikal-T1 System Boot SPI Controller driver");
 341 MODULE_LICENSE("GPL v2");