spi: dw: Add Baikal-T1 SPI Controller glue driver

	tristate "Memory-mapped io interface driver for DW SPI core"

	depends on HAS_IOMEM

config SPI_DW_BT1

	tristate "Baikal-T1 SPI driver for DW SPI core"

	depends on MIPS_BAIKAL_T1 || COMPILE_TEST

	help

	  Baikal-T1 SoC is equipped with three DW APB SSI-based MMIO SPI

	  controllers. Two of them are pretty much normal: with IRQ, DMA,

	  FIFOs of 64 words depth, 4x CSs, but the third one as being a

	  part of the Baikal-T1 System Boot Controller has got a very

	  limited resources: no IRQ, no DMA, only a single native

	  chip-select and Tx/Rx FIFO with just 8 words depth available.

	  The later one is normally connected to an external SPI-nor flash

	  of 128Mb (in general can be of bigger size).

config SPI_DW_BT1_DIRMAP

	bool "Directly mapped Baikal-T1 Boot SPI flash support"

	depends on SPI_DW_BT1

	select MULTIPLEXER

	select MUX_MMIO

	help

	  Directly mapped SPI flash memory is an interface specific to the

	  Baikal-T1 System Boot Controller. It is a 16MB MMIO region, which

	  can be used to access a peripheral memory device just by

	  reading/writing data from/to it. Note that the system APB bus

	  will stall during each IO from/to the dirmap region until the

	  operation is finished. So try not to use it concurrently with

	  time-critical tasks (like the SPI memory operations implemented

	  in this driver).

endif

config SPI_DLN2

obj-$(CONFIG_SPI_DESIGNWARE)		+= spi-dw.o

spi-dw-y				:= spi-dw-core.o

spi-dw-$(CONFIG_SPI_DW_DMA)		+= spi-dw-dma.o

obj-$(CONFIG_SPI_DW_BT1)		+= spi-dw-bt1.o

obj-$(CONFIG_SPI_DW_MMIO)		+= spi-dw-mmio.o

obj-$(CONFIG_SPI_DW_PCI)		+= spi-dw-pci.o

obj-$(CONFIG_SPI_EFM32)			+= spi-efm32.o

// SPDX-License-Identifier: GPL-2.0-only

//

// Copyright (C) 2020 BAIKAL ELECTRONICS, JSC

//

// Authors:

//   Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>

//   Serge Semin <Sergey.Semin@baikalelectronics.ru>

//

// Baikal-T1 DW APB SPI and System Boot SPI driver

//

#include <linux/clk.h>

#include <linux/cpumask.h>

#include <linux/err.h>

#include <linux/interrupt.h>

#include <linux/module.h>

#include <linux/mux/consumer.h>

#include <linux/of.h>

#include <linux/of_platform.h>

#include <linux/platform_device.h>

#include <linux/pm_runtime.h>

#include <linux/property.h>

#include <linux/slab.h>

#include <linux/spi/spi-mem.h>

#include <linux/spi/spi.h>

#include "spi-dw.h"

#define BT1_BOOT_DIRMAP		0

#define BT1_BOOT_REGS		1

struct dw_spi_bt1 {

	struct dw_spi		dws;

	struct clk		*clk;

	struct mux_control	*mux;

#ifdef CONFIG_SPI_DW_BT1_DIRMAP

	void __iomem		*map;

	resource_size_t		map_len;

#endif

};

#define to_dw_spi_bt1(_ctlr) \

	container_of(spi_controller_get_devdata(_ctlr), struct dw_spi_bt1, dws)

typedef int (*dw_spi_bt1_init_cb)(struct platform_device *pdev,

				    struct dw_spi_bt1 *dwsbt1);

#ifdef CONFIG_SPI_DW_BT1_DIRMAP

static int dw_spi_bt1_dirmap_create(struct spi_mem_dirmap_desc *desc)

{

	struct dw_spi_bt1 *dwsbt1 = to_dw_spi_bt1(desc->mem->spi->controller);

	if (!dwsbt1->map ||

	    !dwsbt1->dws.mem_ops.supports_op(desc->mem, &desc->info.op_tmpl))

		return -EOPNOTSUPP;

	/*

	 * Make sure the requested region doesn't go out of the physically

	 * mapped flash memory bounds and the operation is read-only.

	 */

	if (desc->info.offset + desc->info.length > dwsbt1->map_len ||

	    desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)

		return -EOPNOTSUPP;

	return 0;

}

/*

 * Directly mapped SPI memory region is only accessible in the dword chunks.

 * That's why we have to create a dedicated read-method to copy data from there

 * to the passed buffer.

 */

static void dw_spi_bt1_dirmap_copy_from_map(void *to, void __iomem *from, size_t len)

{

	size_t shift, chunk;

	u32 data;

	/*

	 * We split the copying up into the next three stages: unaligned head,

	 * aligned body, unaligned tail.

	 */

	shift = (size_t)from & 0x3;

	if (shift) {

		chunk = min_t(size_t, 4 - shift, len);

		data = readl_relaxed(from - shift);

		memcpy(to, &data + shift, chunk);

		from += chunk;

		to += chunk;

		len -= chunk;

	}

	while (len >= 4) {

		data = readl_relaxed(from);

		memcpy(to, &data, 4);

		from += 4;

		to += 4;

		len -= 4;

	}

	if (len) {

		data = readl_relaxed(from);

		memcpy(to, &data, len);

	}

}

static ssize_t dw_spi_bt1_dirmap_read(struct spi_mem_dirmap_desc *desc,

				      u64 offs, size_t len, void *buf)

{

	struct dw_spi_bt1 *dwsbt1 = to_dw_spi_bt1(desc->mem->spi->controller);

	struct dw_spi *dws = &dwsbt1->dws;

	struct spi_mem *mem = desc->mem;

	struct dw_spi_cfg cfg;

	int ret;

	/*

	 * Make sure the requested operation length is valid. Truncate the

	 * length if it's greater than the length of the MMIO region.

	 */

	if (offs >= dwsbt1->map_len || !len)

		return 0;

	len = min_t(size_t, len, dwsbt1->map_len - offs);

	/* Collect the controller configuration required by the operation */

	cfg.tmode = SPI_TMOD_EPROMREAD;

	cfg.dfs = 8;

	cfg.ndf = 4;

	cfg.freq = mem->spi->max_speed_hz;

	/* Make sure the corresponding CS is de-asserted on transmission */

	dw_spi_set_cs(mem->spi, false);

	spi_enable_chip(dws, 0);

	dw_spi_update_config(dws, mem->spi, &cfg);

	spi_umask_intr(dws, SPI_INT_RXFI);

	spi_enable_chip(dws, 1);

	/*

	 * Enable the transparent mode of the System Boot Controller.

	 * The SPI core IO should have been locked before calling this method

	 * so noone would be touching the controller' registers during the

	 * dirmap operation.

	 */

	ret = mux_control_select(dwsbt1->mux, BT1_BOOT_DIRMAP);

	if (ret)

		return ret;

	dw_spi_bt1_dirmap_copy_from_map(buf, dwsbt1->map + offs, len);

	mux_control_deselect(dwsbt1->mux);

	dw_spi_set_cs(mem->spi, true);

	ret = dw_spi_check_status(dws, true);

	return ret ?: len;

}

#endif /* CONFIG_SPI_DW_BT1_DIRMAP */

static int dw_spi_bt1_std_init(struct platform_device *pdev,

			       struct dw_spi_bt1 *dwsbt1)

{

	struct dw_spi *dws = &dwsbt1->dws;

	dws->irq = platform_get_irq(pdev, 0);

	if (dws->irq < 0)

		return dws->irq;

	dws->num_cs = 4;

	/*

	 * Baikal-T1 Normal SPI Controllers don't always keep up with full SPI

	 * bus speed especially when it comes to the concurrent access to the

	 * APB bus resources. Thus we have no choice but to set a constraint on

	 * the SPI bus frequency for the memory operations which require to

	 * read/write data as fast as possible.

	 */

	dws->max_mem_freq = 20000000U;

	dw_spi_dma_setup_generic(dws);

	return 0;

}

static int dw_spi_bt1_sys_init(struct platform_device *pdev,

			       struct dw_spi_bt1 *dwsbt1)

{

	struct resource *mem __maybe_unused;

	struct dw_spi *dws = &dwsbt1->dws;

	/*

	 * Baikal-T1 System Boot Controller is equipped with a mux, which

	 * switches between the directly mapped SPI flash access mode and

	 * IO access to the DW APB SSI registers. Note the mux controller

	 * must be setup to preserve the registers being accessible by default

	 * (on idle-state).

	 */

	dwsbt1->mux = devm_mux_control_get(&pdev->dev, NULL);

	if (IS_ERR(dwsbt1->mux))

		return PTR_ERR(dwsbt1->mux);

	/*

	 * Directly mapped SPI flash memory is a 16MB MMIO region, which can be

	 * used to access a peripheral memory device just by reading/writing

	 * data from/to it. Note the system APB bus will stall during each IO

	 * from/to the dirmap region until the operation is finished. So don't

	 * use it concurrently with time-critical tasks (like the SPI memory

	 * operations implemented in the DW APB SSI driver).

	 */

#ifdef CONFIG_SPI_DW_BT1_DIRMAP

	mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);

	if (mem) {

		dwsbt1->map = devm_ioremap_resource(&pdev->dev, mem);

		if (!IS_ERR(dwsbt1->map)) {

			dwsbt1->map_len = (mem->end - mem->start + 1);

			dws->mem_ops.dirmap_create = dw_spi_bt1_dirmap_create;

			dws->mem_ops.dirmap_read = dw_spi_bt1_dirmap_read;

		} else {

			dwsbt1->map = NULL;

		}

	}

#endif /* CONFIG_SPI_DW_BT1_DIRMAP */

	/*

	 * There is no IRQ, no DMA and just one CS available on the System Boot

	 * SPI controller.

	 */

	dws->irq = IRQ_NOTCONNECTED;

	dws->num_cs = 1;

	/*

	 * Baikal-T1 System Boot SPI Controller doesn't keep up with the full

	 * SPI bus speed due to relatively slow APB bus and races for it'

	 * resources from different CPUs. The situation is worsen by a small

	 * FIFOs depth (just 8 words). It works better in a single CPU mode

	 * though, but still tends to be not fast enough at low CPU

	 * frequencies.

	 */

	if (num_possible_cpus() > 1)

		dws->max_mem_freq = 10000000U;

	else

		dws->max_mem_freq = 20000000U;

	return 0;

}

static int dw_spi_bt1_probe(struct platform_device *pdev)

{

	dw_spi_bt1_init_cb init_func;

	struct dw_spi_bt1 *dwsbt1;

	struct resource *mem;

	struct dw_spi *dws;

	int ret;

	dwsbt1 = devm_kzalloc(&pdev->dev, sizeof(struct dw_spi_bt1), GFP_KERNEL);

	if (!dwsbt1)

		return -ENOMEM;

	dws = &dwsbt1->dws;

	dws->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);

	if (IS_ERR(dws->regs))

		return PTR_ERR(dws->regs);

	dws->paddr = mem->start;

	dwsbt1->clk = devm_clk_get(&pdev->dev, NULL);

	if (IS_ERR(dwsbt1->clk))

		return PTR_ERR(dwsbt1->clk);

	ret = clk_prepare_enable(dwsbt1->clk);

	if (ret)

		return ret;

	dws->bus_num = pdev->id;

	dws->reg_io_width = 4;

	dws->max_freq = clk_get_rate(dwsbt1->clk);

	if (!dws->max_freq)

		goto err_disable_clk;

	init_func = device_get_match_data(&pdev->dev);

	ret = init_func(pdev, dwsbt1);

	if (ret)

		goto err_disable_clk;

	pm_runtime_enable(&pdev->dev);

	ret = dw_spi_add_host(&pdev->dev, dws);

	if (ret)

		goto err_disable_clk;

	platform_set_drvdata(pdev, dwsbt1);

	return 0;

err_disable_clk:

	clk_disable_unprepare(dwsbt1->clk);

	return ret;

}

static int dw_spi_bt1_remove(struct platform_device *pdev)

{

	struct dw_spi_bt1 *dwsbt1 = platform_get_drvdata(pdev);

	dw_spi_remove_host(&dwsbt1->dws);

	pm_runtime_disable(&pdev->dev);

	clk_disable_unprepare(dwsbt1->clk);

	return 0;

}

static const struct of_device_id dw_spi_bt1_of_match[] = {

	{ .compatible = "baikal,bt1-ssi", .data = dw_spi_bt1_std_init},

	{ .compatible = "baikal,bt1-sys-ssi", .data = dw_spi_bt1_sys_init},

	{ }

};

MODULE_DEVICE_TABLE(of, dw_spi_bt1_of_match);

static struct platform_driver dw_spi_bt1_driver = {

	.probe	= dw_spi_bt1_probe,

	.remove	= dw_spi_bt1_remove,

	.driver	= {

		.name		= "bt1-sys-ssi",

		.of_match_table	= dw_spi_bt1_of_match,

	},

};

module_platform_driver(dw_spi_bt1_driver);

MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");

MODULE_DESCRIPTION("Baikal-T1 System Boot SPI Controller driver");

MODULE_LICENSE("GPL v2");