diff options
Diffstat (limited to 'drivers/mfd/ocelot-spi.c')
| -rw-r--r-- | drivers/mfd/ocelot-spi.c | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/drivers/mfd/ocelot-spi.c b/drivers/mfd/ocelot-spi.c new file mode 100644 index 000000000000..0f097f4829d1 --- /dev/null +++ b/drivers/mfd/ocelot-spi.c @@ -0,0 +1,299 @@ +// SPDX-License-Identifier: (GPL-2.0 OR MIT) +/* + * SPI core driver for the Ocelot chip family. + * + * This driver will handle everything necessary to allow for communication over + * SPI to the VSC7511, VSC7512, VSC7513 and VSC7514 chips. The main functions + * are to prepare the chip's SPI interface for a specific bus speed, and a host + * processor's endianness. This will create and distribute regmaps for any + * children. + * + * Copyright 2021-2022 Innovative Advantage Inc. + * + * Author: Colin Foster <colin.foster@in-advantage.com> + */ + +#include <linux/device.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/export.h> +#include <linux/ioport.h> +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/regmap.h> +#include <linux/spi/spi.h> +#include <linux/types.h> +#include <linux/units.h> + +#include "ocelot.h" + +#define REG_DEV_CPUORG_IF_CTRL 0x0000 +#define REG_DEV_CPUORG_IF_CFGSTAT 0x0004 + +#define CFGSTAT_IF_NUM_VCORE (0 << 24) +#define CFGSTAT_IF_NUM_VRAP (1 << 24) +#define CFGSTAT_IF_NUM_SI (2 << 24) +#define CFGSTAT_IF_NUM_MIIM (3 << 24) + +#define VSC7512_DEVCPU_ORG_RES_START 0x71000000 +#define VSC7512_DEVCPU_ORG_RES_SIZE 0x38 + +#define VSC7512_CHIP_REGS_RES_START 0x71070000 +#define VSC7512_CHIP_REGS_RES_SIZE 0x14 + +static const struct resource vsc7512_dev_cpuorg_resource = + DEFINE_RES_REG_NAMED(VSC7512_DEVCPU_ORG_RES_START, + VSC7512_DEVCPU_ORG_RES_SIZE, + "devcpu_org"); + +static const struct resource vsc7512_gcb_resource = + DEFINE_RES_REG_NAMED(VSC7512_CHIP_REGS_RES_START, + VSC7512_CHIP_REGS_RES_SIZE, + "devcpu_gcb_chip_regs"); + +static int ocelot_spi_initialize(struct device *dev) +{ + struct ocelot_ddata *ddata = dev_get_drvdata(dev); + u32 val, check; + int err; + + val = OCELOT_SPI_BYTE_ORDER; + + /* + * The SPI address must be big-endian, but we want the payload to match + * our CPU. These are two bits (0 and 1) but they're repeated such that + * the write from any configuration will be valid. The four + * configurations are: + * + * 0b00: little-endian, MSB first + * | 111111 | 22221111 | 33222222 | + * | 76543210 | 54321098 | 32109876 | 10987654 | + * + * 0b01: big-endian, MSB first + * | 33222222 | 22221111 | 111111 | | + * | 10987654 | 32109876 | 54321098 | 76543210 | + * + * 0b10: little-endian, LSB first + * | 111111 | 11112222 | 22222233 | + * | 01234567 | 89012345 | 67890123 | 45678901 | + * + * 0b11: big-endian, LSB first + * | 22222233 | 11112222 | 111111 | | + * | 45678901 | 67890123 | 89012345 | 01234567 | + */ + err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CTRL, val); + if (err) + return err; + + /* + * Apply the number of padding bytes between a read request and the data + * payload. Some registers have access times of up to 1us, so if the + * first payload bit is shifted out too quickly, the read will fail. + */ + val = ddata->spi_padding_bytes; + err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, val); + if (err) + return err; + + /* + * After we write the interface configuration, read it back here. This + * will verify several different things. The first is that the number of + * padding bytes actually got written correctly. These are found in bits + * 0:3. + * + * The second is that bit 16 is cleared. Bit 16 is IF_CFGSTAT:IF_STAT, + * and will be set if the register access is too fast. This would be in + * the condition that the number of padding bytes is insufficient for + * the SPI bus frequency. + * + * The last check is for bits 31:24, which define the interface by which + * the registers are being accessed. Since we're accessing them via the + * serial interface, it must return IF_NUM_SI. + */ + check = val | CFGSTAT_IF_NUM_SI; + + err = regmap_read(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, &val); + if (err) + return err; + + if (check != val) + return -ENODEV; + + return 0; +} + +static const struct regmap_config ocelot_spi_regmap_config = { + .reg_bits = 24, + .reg_stride = 4, + .reg_downshift = 2, + .val_bits = 32, + + .write_flag_mask = 0x80, + + .use_single_write = true, + .can_multi_write = false, + + .reg_format_endian = REGMAP_ENDIAN_BIG, + .val_format_endian = REGMAP_ENDIAN_NATIVE, +}; + +static int ocelot_spi_regmap_bus_read(void *context, const void *reg, size_t reg_size, + void *val, size_t val_size) +{ + struct spi_transfer xfers[3] = {0}; + struct device *dev = context; + struct ocelot_ddata *ddata; + struct spi_device *spi; + struct spi_message msg; + unsigned int index = 0; + + ddata = dev_get_drvdata(dev); + spi = to_spi_device(dev); + + xfers[index].tx_buf = reg; + xfers[index].len = reg_size; + index++; + + if (ddata->spi_padding_bytes) { + xfers[index].len = ddata->spi_padding_bytes; + xfers[index].tx_buf = ddata->dummy_buf; + xfers[index].dummy_data = 1; + index++; + } + + xfers[index].rx_buf = val; + xfers[index].len = val_size; + index++; + + spi_message_init_with_transfers(&msg, xfers, index); + + return spi_sync(spi, &msg); +} + +static int ocelot_spi_regmap_bus_write(void *context, const void *data, size_t count) +{ + struct device *dev = context; + struct spi_device *spi = to_spi_device(dev); + + return spi_write(spi, data, count); +} + +static const struct regmap_bus ocelot_spi_regmap_bus = { + .write = ocelot_spi_regmap_bus_write, + .read = ocelot_spi_regmap_bus_read, +}; + +struct regmap *ocelot_spi_init_regmap(struct device *dev, const struct resource *res) +{ + struct regmap_config regmap_config; + + memcpy(®map_config, &ocelot_spi_regmap_config, sizeof(regmap_config)); + + regmap_config.name = res->name; + regmap_config.max_register = resource_size(res) - 1; + regmap_config.reg_base = res->start; + + return devm_regmap_init(dev, &ocelot_spi_regmap_bus, dev, ®map_config); +} +EXPORT_SYMBOL_NS(ocelot_spi_init_regmap, MFD_OCELOT_SPI); + +static int ocelot_spi_probe(struct spi_device *spi) +{ + struct device *dev = &spi->dev; + struct ocelot_ddata *ddata; + struct regmap *r; + int err; + + ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL); + if (!ddata) + return -ENOMEM; + + spi_set_drvdata(spi, ddata); + + if (spi->max_speed_hz <= 500000) { + ddata->spi_padding_bytes = 0; + } else { + /* + * Calculation taken from the manual for IF_CFGSTAT:IF_CFG. + * Register access time is 1us, so we need to configure and send + * out enough padding bytes between the read request and data + * transmission that lasts at least 1 microsecond. + */ + ddata->spi_padding_bytes = 1 + (spi->max_speed_hz / HZ_PER_MHZ + 2) / 8; + + ddata->dummy_buf = devm_kzalloc(dev, ddata->spi_padding_bytes, GFP_KERNEL); + if (!ddata->dummy_buf) + return -ENOMEM; + } + + spi->bits_per_word = 8; + + err = spi_setup(spi); + if (err) + return dev_err_probe(&spi->dev, err, "Error performing SPI setup\n"); + + r = ocelot_spi_init_regmap(dev, &vsc7512_dev_cpuorg_resource); + if (IS_ERR(r)) + return PTR_ERR(r); + + ddata->cpuorg_regmap = r; + + r = ocelot_spi_init_regmap(dev, &vsc7512_gcb_resource); + if (IS_ERR(r)) + return PTR_ERR(r); + + ddata->gcb_regmap = r; + + /* + * The chip must be set up for SPI before it gets initialized and reset. + * This must be done before calling init, and after a chip reset is + * performed. + */ + err = ocelot_spi_initialize(dev); + if (err) + return dev_err_probe(dev, err, "Error initializing SPI bus\n"); + + err = ocelot_chip_reset(dev); + if (err) + return dev_err_probe(dev, err, "Error resetting device\n"); + + /* + * A chip reset will clear the SPI configuration, so it needs to be done + * again before we can access any registers. + */ + err = ocelot_spi_initialize(dev); + if (err) + return dev_err_probe(dev, err, "Error initializing SPI bus after reset\n"); + + err = ocelot_core_init(dev); + if (err) + return dev_err_probe(dev, err, "Error initializing Ocelot core\n"); + + return 0; +} + +static const struct spi_device_id ocelot_spi_ids[] = { + { "vsc7512", 0 }, + { } +}; + +static const struct of_device_id ocelot_spi_of_match[] = { + { .compatible = "mscc,vsc7512" }, + { } +}; +MODULE_DEVICE_TABLE(of, ocelot_spi_of_match); + +static struct spi_driver ocelot_spi_driver = { + .driver = { + .name = "ocelot-soc", + .of_match_table = ocelot_spi_of_match, + }, + .id_table = ocelot_spi_ids, + .probe = ocelot_spi_probe, +}; +module_spi_driver(ocelot_spi_driver); + +MODULE_DESCRIPTION("SPI Controlled Ocelot Chip Driver"); +MODULE_AUTHOR("Colin Foster <colin.foster@in-advantage.com>"); +MODULE_LICENSE("Dual MIT/GPL"); +MODULE_IMPORT_NS(MFD_OCELOT); |