// SPDX-License-Identifier: GPL-2.0+ /* Realtek Simple Management Interface (SMI) driver * It can be discussed how "simple" this interface is. * * The SMI protocol piggy-backs the MDIO MDC and MDIO signals levels * but the protocol is not MDIO at all. Instead it is a Realtek * pecularity that need to bit-bang the lines in a special way to * communicate with the switch. * * ASICs we intend to support with this driver: * * RTL8366 - The original version, apparently * RTL8369 - Similar enough to have the same datsheet as RTL8366 * RTL8366RB - Probably reads out "RTL8366 revision B", has a quite * different register layout from the other two * RTL8366S - Is this "RTL8366 super"? * RTL8367 - Has an OpenWRT driver as well * RTL8368S - Seems to be an alternative name for RTL8366RB * RTL8370 - Also uses SMI * * Copyright (C) 2017 Linus Walleij * Copyright (C) 2010 Antti Seppälä * Copyright (C) 2010 Roman Yeryomin * Copyright (C) 2011 Colin Leitner * Copyright (C) 2009-2010 Gabor Juhos */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "realtek-smi.h" #define REALTEK_SMI_ACK_RETRY_COUNT 5 #define REALTEK_SMI_HW_STOP_DELAY 25 /* msecs */ #define REALTEK_SMI_HW_START_DELAY 100 /* msecs */ static inline void realtek_smi_clk_delay(struct realtek_smi *smi) { ndelay(smi->clk_delay); } static void realtek_smi_start(struct realtek_smi *smi) { /* Set GPIO pins to output mode, with initial state: * SCK = 0, SDA = 1 */ gpiod_direction_output(smi->mdc, 0); gpiod_direction_output(smi->mdio, 1); realtek_smi_clk_delay(smi); /* CLK 1: 0 -> 1, 1 -> 0 */ gpiod_set_value(smi->mdc, 1); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdc, 0); realtek_smi_clk_delay(smi); /* CLK 2: */ gpiod_set_value(smi->mdc, 1); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdio, 0); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdc, 0); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdio, 1); } static void realtek_smi_stop(struct realtek_smi *smi) { realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdio, 0); gpiod_set_value(smi->mdc, 1); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdio, 1); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdc, 1); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdc, 0); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdc, 1); /* Add a click */ realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdc, 0); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdc, 1); /* Set GPIO pins to input mode */ gpiod_direction_input(smi->mdio); gpiod_direction_input(smi->mdc); } static void realtek_smi_write_bits(struct realtek_smi *smi, u32 data, u32 len) { for (; len > 0; len--) { realtek_smi_clk_delay(smi); /* Prepare data */ gpiod_set_value(smi->mdio, !!(data & (1 << (len - 1)))); realtek_smi_clk_delay(smi); /* Clocking */ gpiod_set_value(smi->mdc, 1); realtek_smi_clk_delay(smi); gpiod_set_value(smi->mdc, 0); } } static void realtek_smi_read_bits(struct realtek_smi *smi, u32 len, u32 *data) { gpiod_direction_input(smi->mdio); for (*data = 0; len > 0; len--) { u32 u; realtek_smi_clk_delay(smi); /* Clocking */ gpiod_set_value(smi->mdc, 1); realtek_smi_clk_delay(smi); u = !!gpiod_get_value(smi->mdio); gpiod_set_value(smi->mdc, 0); *data |= (u << (len - 1)); } gpiod_direction_output(smi->mdio, 0); } static int realtek_smi_wait_for_ack(struct realtek_smi *smi) { int retry_cnt; retry_cnt = 0; do { u32 ack; realtek_smi_read_bits(smi, 1, &ack); if (ack == 0) break; if (++retry_cnt > REALTEK_SMI_ACK_RETRY_COUNT) { dev_err(smi->dev, "ACK timeout\n"); return -ETIMEDOUT; } } while (1); return 0; } static int realtek_smi_write_byte(struct realtek_smi *smi, u8 data) { realtek_smi_write_bits(smi, data, 8); return realtek_smi_wait_for_ack(smi); } static int realtek_smi_write_byte_noack(struct realtek_smi *smi, u8 data) { realtek_smi_write_bits(smi, data, 8); return 0; } static int realtek_smi_read_byte0(struct realtek_smi *smi, u8 *data) { u32 t; /* Read data */ realtek_smi_read_bits(smi, 8, &t); *data = (t & 0xff); /* Send an ACK */ realtek_smi_write_bits(smi, 0x00, 1); return 0; } static int realtek_smi_read_byte1(struct realtek_smi *smi, u8 *data) { u32 t; /* Read data */ realtek_smi_read_bits(smi, 8, &t); *data = (t & 0xff); /* Send an ACK */ realtek_smi_write_bits(smi, 0x01, 1); return 0; } static int realtek_smi_read_reg(struct realtek_smi *smi, u32 addr, u32 *data) { unsigned long flags; u8 lo = 0; u8 hi = 0; int ret; spin_lock_irqsave(&smi->lock, flags); realtek_smi_start(smi); /* Send READ command */ ret = realtek_smi_write_byte(smi, smi->cmd_read); if (ret) goto out; /* Set ADDR[7:0] */ ret = realtek_smi_write_byte(smi, addr & 0xff); if (ret) goto out; /* Set ADDR[15:8] */ ret = realtek_smi_write_byte(smi, addr >> 8); if (ret) goto out; /* Read DATA[7:0] */ realtek_smi_read_byte0(smi, &lo); /* Read DATA[15:8] */ realtek_smi_read_byte1(smi, &hi); *data = ((u32)lo) | (((u32)hi) << 8); ret = 0; out: realtek_smi_stop(smi); spin_unlock_irqrestore(&smi->lock, flags); return ret; } static int realtek_smi_write_reg(struct realtek_smi *smi, u32 addr, u32 data, bool ack) { unsigned long flags; int ret; spin_lock_irqsave(&smi->lock, flags); realtek_smi_start(smi); /* Send WRITE command */ ret = realtek_smi_write_byte(smi, smi->cmd_write); if (ret) goto out; /* Set ADDR[7:0] */ ret = realtek_smi_write_byte(smi, addr & 0xff); if (ret) goto out; /* Set ADDR[15:8] */ ret = realtek_smi_write_byte(smi, addr >> 8); if (ret) goto out; /* Write DATA[7:0] */ ret = realtek_smi_write_byte(smi, data & 0xff); if (ret) goto out; /* Write DATA[15:8] */ if (ack) ret = realtek_smi_write_byte(smi, data >> 8); else ret = realtek_smi_write_byte_noack(smi, data >> 8); if (ret) goto out; ret = 0; out: realtek_smi_stop(smi); spin_unlock_irqrestore(&smi->lock, flags); return ret; } /* There is one single case when we need to use this accessor and that * is when issueing soft reset. Since the device reset as soon as we write * that bit, no ACK will come back for natural reasons. */ int realtek_smi_write_reg_noack(struct realtek_smi *smi, u32 addr, u32 data) { return realtek_smi_write_reg(smi, addr, data, false); } EXPORT_SYMBOL_GPL(realtek_smi_write_reg_noack); /* Regmap accessors */ static int realtek_smi_write(void *ctx, u32 reg, u32 val) { struct realtek_smi *smi = ctx; return realtek_smi_write_reg(smi, reg, val, true); } static int realtek_smi_read(void *ctx, u32 reg, u32 *val) { struct realtek_smi *smi = ctx; return realtek_smi_read_reg(smi, reg, val); } static const struct regmap_config realtek_smi_mdio_regmap_config = { .reg_bits = 10, /* A4..A0 R4..R0 */ .val_bits = 16, .reg_stride = 1, /* PHY regs are at 0x8000 */ .max_register = 0xffff, .reg_format_endian = REGMAP_ENDIAN_BIG, .reg_read = realtek_smi_read, .reg_write = realtek_smi_write, .cache_type = REGCACHE_NONE, }; static int realtek_smi_mdio_read(struct mii_bus *bus, int addr, int regnum) { struct realtek_smi *smi = bus->priv; return smi->ops->phy_read(smi, addr, regnum); } static int realtek_smi_mdio_write(struct mii_bus *bus, int addr, int regnum, u16 val) { struct realtek_smi *smi = bus->priv; return smi->ops->phy_write(smi, addr, regnum, val); } int realtek_smi_setup_mdio(struct realtek_smi *smi) { struct device_node *mdio_np; int ret; mdio_np = of_get_compatible_child(smi->dev->of_node, "realtek,smi-mdio"); if (!mdio_np) { dev_err(smi->dev, "no MDIO bus node\n"); return -ENODEV; } smi->slave_mii_bus = devm_mdiobus_alloc(smi->dev); if (!smi->slave_mii_bus) { ret = -ENOMEM; goto err_put_node; } smi->slave_mii_bus->priv = smi; smi->slave_mii_bus->name = "SMI slave MII"; smi->slave_mii_bus->read = realtek_smi_mdio_read; smi->slave_mii_bus->write = realtek_smi_mdio_write; snprintf(smi->slave_mii_bus->id, MII_BUS_ID_SIZE, "SMI-%d", smi->ds->index); smi->slave_mii_bus->dev.of_node = mdio_np; smi->slave_mii_bus->parent = smi->dev; smi->ds->slave_mii_bus = smi->slave_mii_bus; ret = of_mdiobus_register(smi->slave_mii_bus, mdio_np); if (ret) { dev_err(smi->dev, "unable to register MDIO bus %s\n", smi->slave_mii_bus->id); goto err_put_node; } return 0; err_put_node: of_node_put(mdio_np); return ret; } static int realtek_smi_probe(struct platform_device *pdev) { const struct realtek_smi_variant *var; struct device *dev = &pdev->dev; struct realtek_smi *smi; struct device_node *np; int ret; var = of_device_get_match_data(dev); np = dev->of_node; smi = devm_kzalloc(dev, sizeof(*smi), GFP_KERNEL); if (!smi) return -ENOMEM; smi->map = devm_regmap_init(dev, NULL, smi, &realtek_smi_mdio_regmap_config); if (IS_ERR(smi->map)) { ret = PTR_ERR(smi->map); dev_err(dev, "regmap init failed: %d\n", ret); return ret; } /* Link forward and backward */ smi->dev = dev; smi->clk_delay = var->clk_delay; smi->cmd_read = var->cmd_read; smi->cmd_write = var->cmd_write; smi->ops = var->ops; dev_set_drvdata(dev, smi); spin_lock_init(&smi->lock); /* TODO: if power is software controlled, set up any regulators here */ /* Assert then deassert RESET */ smi->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); if (IS_ERR(smi->reset)) { dev_err(dev, "failed to get RESET GPIO\n"); return PTR_ERR(smi->reset); } msleep(REALTEK_SMI_HW_STOP_DELAY); gpiod_set_value(smi->reset, 0); msleep(REALTEK_SMI_HW_START_DELAY); dev_info(dev, "deasserted RESET\n"); /* Fetch MDIO pins */ smi->mdc = devm_gpiod_get_optional(dev, "mdc", GPIOD_OUT_LOW); if (IS_ERR(smi->mdc)) return PTR_ERR(smi->mdc); smi->mdio = devm_gpiod_get_optional(dev, "mdio", GPIOD_OUT_LOW); if (IS_ERR(smi->mdio)) return PTR_ERR(smi->mdio); smi->leds_disabled = of_property_read_bool(np, "realtek,disable-leds"); ret = smi->ops->detect(smi); if (ret) { dev_err(dev, "unable to detect switch\n"); return ret; } smi->ds = dsa_switch_alloc(dev, smi->num_ports); if (!smi->ds) return -ENOMEM; smi->ds->priv = smi; smi->ds->ops = var->ds_ops; ret = dsa_register_switch(smi->ds); if (ret) { dev_err(dev, "unable to register switch ret = %d\n", ret); return ret; } return 0; } static int realtek_smi_remove(struct platform_device *pdev) { struct realtek_smi *smi = dev_get_drvdata(&pdev->dev); dsa_unregister_switch(smi->ds); if (smi->slave_mii_bus) of_node_put(smi->slave_mii_bus->dev.of_node); gpiod_set_value(smi->reset, 1); return 0; } static const struct of_device_id realtek_smi_of_match[] = { { .compatible = "realtek,rtl8366rb", .data = &rtl8366rb_variant, }, { /* FIXME: add support for RTL8366S and more */ .compatible = "realtek,rtl8366s", .data = NULL, }, { /* sentinel */ }, }; MODULE_DEVICE_TABLE(of, realtek_smi_of_match); static struct platform_driver realtek_smi_driver = { .driver = { .name = "realtek-smi", .of_match_table = of_match_ptr(realtek_smi_of_match), }, .probe = realtek_smi_probe, .remove = realtek_smi_remove, }; module_platform_driver(realtek_smi_driver); MODULE_LICENSE("GPL");