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         if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
  59                 return -EOPNOTSUPP;
  60
  61         /*
  62          * Make sure the requested region doesn't go out of the physically
  63          * mapped flash memory bounds.
  64          */
  65         if (desc->info.offset + desc->info.length > dwsbt1->map_len)
  66                 return -EINVAL;
  67
  68         return 0;
  69 }
  70
  71 /*
  72  * Directly mapped SPI memory region is only accessible in the dword chunks.
  73  * That's why we have to create a dedicated read-method to copy data from there
  74  * to the passed buffer.
  75  */
  76 static void dw_spi_bt1_dirmap_copy_from_map(void *to, void __iomem *from, size_t len)
  77 {
  78         size_t shift, chunk;
  79         u32 data;
  80
  81         /*
  82          * We split the copying up into the next three stages: unaligned head,
  83          * aligned body, unaligned tail.
  84          */
  85         shift = (size_t)from & 0x3;
  86         if (shift) {
  87                 chunk = min_t(size_t, 4 - shift, len);
  88                 data = readl_relaxed(from - shift);
  89                 memcpy(to, (char *)&data + shift, chunk);
  90                 from += chunk;
  91                 to += chunk;
  92                 len -= chunk;
  93         }
  94
  95         while (len >= 4) {
  96                 data = readl_relaxed(from);
  97                 memcpy(to, &data, 4);
  98                 from += 4;
  99                 to += 4;
 100                 len -= 4;
 101         }
 102
 103         if (len) {
 104                 data = readl_relaxed(from);
 105                 memcpy(to, &data, len);
 106         }
 107 }
 108
 109 static ssize_t dw_spi_bt1_dirmap_read(struct spi_mem_dirmap_desc *desc,
 110                                       u64 offs, size_t len, void *buf)
 111 {
 112         struct dw_spi_bt1 *dwsbt1 = to_dw_spi_bt1(desc->mem->spi->controller);
 113         struct dw_spi *dws = &dwsbt1->dws;
 114         struct spi_mem *mem = desc->mem;
 115         struct dw_spi_cfg cfg;
 116         int ret;
 117
 118         /*
 119          * Make sure the requested operation length is valid. Truncate the
 120          * length if it's greater than the length of the MMIO region.
 121          */
 122         if (offs >= dwsbt1->map_len || !len)
 123                 return 0;
 124
 125         len = min_t(size_t, len, dwsbt1->map_len - offs);
 126
 127         /* Collect the controller configuration required by the operation */
 128         cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;
 129         cfg.dfs = 8;
 130         cfg.ndf = 4;
 131         cfg.freq = mem->spi->max_speed_hz;
 132
 133         /* Make sure the corresponding CS is de-asserted on transmission */
 134         dw_spi_set_cs(mem->spi, false);
 135
 136         dw_spi_enable_chip(dws, 0);
 137
 138         dw_spi_update_config(dws, mem->spi, &cfg);
 139
 140         dw_spi_umask_intr(dws, DW_SPI_INT_RXFI);
 141
 142         dw_spi_enable_chip(dws, 1);
 143
 144         /*
 145          * Enable the transparent mode of the System Boot Controller.
 146          * The SPI core IO should have been locked before calling this method
 147          * so noone would be touching the controller' registers during the
 148          * dirmap operation.
 149          */
 150         ret = mux_control_select(dwsbt1->mux, BT1_BOOT_DIRMAP);
 151         if (ret)
 152                 return ret;
 153
 154         dw_spi_bt1_dirmap_copy_from_map(buf, dwsbt1->map + offs, len);
 155
 156         mux_control_deselect(dwsbt1->mux);
 157
 158         dw_spi_set_cs(mem->spi, true);
 159
 160         ret = dw_spi_check_status(dws, true);
 161
 162         return ret ?: len;
 163 }
 164
 165 #endif /* CONFIG_SPI_DW_BT1_DIRMAP */
 166
 167 static int dw_spi_bt1_std_init(struct platform_device *pdev,
 168                                struct dw_spi_bt1 *dwsbt1)
 169 {
 170         struct dw_spi *dws = &dwsbt1->dws;
 171
 172         dws->irq = platform_get_irq(pdev, 0);
 173         if (dws->irq < 0)
 174                 return dws->irq;
 175
 176         dws->num_cs = 4;
 177
 178         /*
 179          * Baikal-T1 Normal SPI Controllers don't always keep up with full SPI
 180          * bus speed especially when it comes to the concurrent access to the
 181          * APB bus resources. Thus we have no choice but to set a constraint on
 182          * the SPI bus frequency for the memory operations which require to
 183          * read/write data as fast as possible.
 184          */
 185         dws->max_mem_freq = 20000000U;
 186
 187         dw_spi_dma_setup_generic(dws);
 188
 189         return 0;
 190 }
 191
 192 static int dw_spi_bt1_sys_init(struct platform_device *pdev,
 193                                struct dw_spi_bt1 *dwsbt1)
 194 {
 195         struct resource *mem __maybe_unused;
 196         struct dw_spi *dws = &dwsbt1->dws;
 197
 198         /*
 199          * Baikal-T1 System Boot Controller is equipped with a mux, which
 200          * switches between the directly mapped SPI flash access mode and
 201          * IO access to the DW APB SSI registers. Note the mux controller
 202          * must be setup to preserve the registers being accessible by default
 203          * (on idle-state).
 204          */
 205         dwsbt1->mux = devm_mux_control_get(&pdev->dev, NULL);
 206         if (IS_ERR(dwsbt1->mux))
 207                 return PTR_ERR(dwsbt1->mux);
 208
 209         /*
 210          * Directly mapped SPI flash memory is a 16MB MMIO region, which can be
 211          * used to access a peripheral memory device just by reading/writing
 212          * data from/to it. Note the system APB bus will stall during each IO
 213          * from/to the dirmap region until the operation is finished. So don't
 214          * use it concurrently with time-critical tasks (like the SPI memory
 215          * operations implemented in the DW APB SSI driver).
 216          */
 217 #ifdef CONFIG_SPI_DW_BT1_DIRMAP
 218         mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 219         if (mem) {
 220                 dwsbt1->map = devm_ioremap_resource(&pdev->dev, mem);
 221                 if (!IS_ERR(dwsbt1->map)) {
 222                         dwsbt1->map_len = resource_size(mem);
 223                         dws->mem_ops.dirmap_create = dw_spi_bt1_dirmap_create;
 224                         dws->mem_ops.dirmap_read = dw_spi_bt1_dirmap_read;
 225                 } else {
 226                         dwsbt1->map = NULL;
 227                 }
 228         }
 229 #endif /* CONFIG_SPI_DW_BT1_DIRMAP */
 230
 231         /*
 232          * There is no IRQ, no DMA and just one CS available on the System Boot
 233          * SPI controller.
 234          */
 235         dws->irq = IRQ_NOTCONNECTED;
 236         dws->num_cs = 1;
 237
 238         /*
 239          * Baikal-T1 System Boot SPI Controller doesn't keep up with the full
 240          * SPI bus speed due to relatively slow APB bus and races for it'
 241          * resources from different CPUs. The situation is worsen by a small
 242          * FIFOs depth (just 8 words). It works better in a single CPU mode
 243          * though, but still tends to be not fast enough at low CPU
 244          * frequencies.
 245          */
 246         if (num_possible_cpus() > 1)
 247                 dws->max_mem_freq = 10000000U;
 248         else
 249                 dws->max_mem_freq = 20000000U;
 250
 251         return 0;
 252 }
 253
 254 static int dw_spi_bt1_probe(struct platform_device *pdev)
 255 {
 256         dw_spi_bt1_init_cb init_func;
 257         struct dw_spi_bt1 *dwsbt1;
 258         struct resource *mem;
 259         struct dw_spi *dws;
 260         int ret;
 261
 262         dwsbt1 = devm_kzalloc(&pdev->dev, sizeof(struct dw_spi_bt1), GFP_KERNEL);
 263         if (!dwsbt1)
 264                 return -ENOMEM;
 265
 266         dws = &dwsbt1->dws;
 267
 268         dws->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);
 269         if (IS_ERR(dws->regs))
 270                 return PTR_ERR(dws->regs);
 271
 272         dws->paddr = mem->start;
 273
 274         dwsbt1->clk = devm_clk_get_enabled(&pdev->dev, NULL);
 275         if (IS_ERR(dwsbt1->clk))
 276                 return PTR_ERR(dwsbt1->clk);
 277
 278         dws->bus_num = pdev->id;
 279         dws->reg_io_width = 4;
 280         dws->max_freq = clk_get_rate(dwsbt1->clk);
 281         if (!dws->max_freq)
 282                 return -EINVAL;
 283
 284         init_func = device_get_match_data(&pdev->dev);
 285         ret = init_func(pdev, dwsbt1);
 286         if (ret)
 287                 return ret;
 288
 289         pm_runtime_enable(&pdev->dev);
 290
 291         ret = dw_spi_add_host(&pdev->dev, dws);
 292         if (ret) {
 293                 pm_runtime_disable(&pdev->dev);
 294                 return ret;
 295         }
 296
 297         platform_set_drvdata(pdev, dwsbt1);
 298
 299         return 0;
 300 }
 301
 302 static void dw_spi_bt1_remove(struct platform_device *pdev)
 303 {
 304         struct dw_spi_bt1 *dwsbt1 = platform_get_drvdata(pdev);
 305
 306         dw_spi_remove_host(&dwsbt1->dws);
 307
 308         pm_runtime_disable(&pdev->dev);
 309 }
 310
 311 static const struct of_device_id dw_spi_bt1_of_match[] = {
 312         { .compatible = "baikal,bt1-ssi", .data = dw_spi_bt1_std_init},
 313         { .compatible = "baikal,bt1-sys-ssi", .data = dw_spi_bt1_sys_init},
 314         { }
 315 };
 316 MODULE_DEVICE_TABLE(of, dw_spi_bt1_of_match);
 317
 318 static struct platform_driver dw_spi_bt1_driver = {
 319         .probe  = dw_spi_bt1_probe,
 320         .remove_new = dw_spi_bt1_remove,
 321         .driver = {
 322                 .name           = "bt1-sys-ssi",
 323                 .of_match_table = dw_spi_bt1_of_match,
 324         },
 325 };
 326 module_platform_driver(dw_spi_bt1_driver);
 327
 328 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
 329 MODULE_DESCRIPTION("Baikal-T1 System Boot SPI Controller driver");
 330 MODULE_LICENSE("GPL v2");
 331 MODULE_IMPORT_NS(SPI_DW_CORE);