diff options
Diffstat (limited to 'drivers/soc/samsung/exynos-usi.c')
| -rw-r--r-- | drivers/soc/samsung/exynos-usi.c | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/drivers/soc/samsung/exynos-usi.c b/drivers/soc/samsung/exynos-usi.c new file mode 100644 index 000000000..114352695 --- /dev/null +++ b/drivers/soc/samsung/exynos-usi.c @@ -0,0 +1,285 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2021 Linaro Ltd. + * Author: Sam Protsenko <semen.protsenko@linaro.org> + * + * Samsung Exynos USI driver (Universal Serial Interface). + */ + +#include <linux/clk.h> +#include <linux/mfd/syscon.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_platform.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> + +#include <dt-bindings/soc/samsung,exynos-usi.h> + +/* USIv2: System Register: SW_CONF register bits */ +#define USI_V2_SW_CONF_NONE 0x0 +#define USI_V2_SW_CONF_UART BIT(0) +#define USI_V2_SW_CONF_SPI BIT(1) +#define USI_V2_SW_CONF_I2C BIT(2) +#define USI_V2_SW_CONF_MASK (USI_V2_SW_CONF_UART | USI_V2_SW_CONF_SPI | \ + USI_V2_SW_CONF_I2C) + +/* USIv2: USI register offsets */ +#define USI_CON 0x04 +#define USI_OPTION 0x08 + +/* USIv2: USI register bits */ +#define USI_CON_RESET BIT(0) +#define USI_OPTION_CLKREQ_ON BIT(1) +#define USI_OPTION_CLKSTOP_ON BIT(2) + +enum exynos_usi_ver { + USI_VER2 = 2, +}; + +struct exynos_usi_variant { + enum exynos_usi_ver ver; /* USI IP-core version */ + unsigned int sw_conf_mask; /* SW_CONF mask for all protocols */ + size_t min_mode; /* first index in exynos_usi_modes[] */ + size_t max_mode; /* last index in exynos_usi_modes[] */ + size_t num_clks; /* number of clocks to assert */ + const char * const *clk_names; /* clock names to assert */ +}; + +struct exynos_usi { + struct device *dev; + void __iomem *regs; /* USI register map */ + struct clk_bulk_data *clks; /* USI clocks */ + + size_t mode; /* current USI SW_CONF mode index */ + bool clkreq_on; /* always provide clock to IP */ + + /* System Register */ + struct regmap *sysreg; /* System Register map */ + unsigned int sw_conf; /* SW_CONF register offset in sysreg */ + + const struct exynos_usi_variant *data; +}; + +struct exynos_usi_mode { + const char *name; /* mode name */ + unsigned int val; /* mode register value */ +}; + +static const struct exynos_usi_mode exynos_usi_modes[] = { + [USI_V2_NONE] = { .name = "none", .val = USI_V2_SW_CONF_NONE }, + [USI_V2_UART] = { .name = "uart", .val = USI_V2_SW_CONF_UART }, + [USI_V2_SPI] = { .name = "spi", .val = USI_V2_SW_CONF_SPI }, + [USI_V2_I2C] = { .name = "i2c", .val = USI_V2_SW_CONF_I2C }, +}; + +static const char * const exynos850_usi_clk_names[] = { "pclk", "ipclk" }; +static const struct exynos_usi_variant exynos850_usi_data = { + .ver = USI_VER2, + .sw_conf_mask = USI_V2_SW_CONF_MASK, + .min_mode = USI_V2_NONE, + .max_mode = USI_V2_I2C, + .num_clks = ARRAY_SIZE(exynos850_usi_clk_names), + .clk_names = exynos850_usi_clk_names, +}; + +static const struct of_device_id exynos_usi_dt_match[] = { + { + .compatible = "samsung,exynos850-usi", + .data = &exynos850_usi_data, + }, + { } /* sentinel */ +}; +MODULE_DEVICE_TABLE(of, exynos_usi_dt_match); + +/** + * exynos_usi_set_sw_conf - Set USI block configuration mode + * @usi: USI driver object + * @mode: Mode index + * + * Select underlying serial protocol (UART/SPI/I2C) in USI IP-core. + * + * Return: 0 on success, or negative error code on failure. + */ +static int exynos_usi_set_sw_conf(struct exynos_usi *usi, size_t mode) +{ + unsigned int val; + int ret; + + if (mode < usi->data->min_mode || mode > usi->data->max_mode) + return -EINVAL; + + val = exynos_usi_modes[mode].val; + ret = regmap_update_bits(usi->sysreg, usi->sw_conf, + usi->data->sw_conf_mask, val); + if (ret) + return ret; + + usi->mode = mode; + dev_dbg(usi->dev, "protocol: %s\n", exynos_usi_modes[usi->mode].name); + + return 0; +} + +/** + * exynos_usi_enable - Initialize USI block + * @usi: USI driver object + * + * USI IP-core start state is "reset" (on startup and after CPU resume). This + * routine enables the USI block by clearing the reset flag. It also configures + * HWACG behavior (needed e.g. for UART Rx). It should be performed before + * underlying protocol becomes functional. + * + * Return: 0 on success, or negative error code on failure. + */ +static int exynos_usi_enable(const struct exynos_usi *usi) +{ + u32 val; + int ret; + + ret = clk_bulk_prepare_enable(usi->data->num_clks, usi->clks); + if (ret) + return ret; + + /* Enable USI block */ + val = readl(usi->regs + USI_CON); + val &= ~USI_CON_RESET; + writel(val, usi->regs + USI_CON); + udelay(1); + + /* Continuously provide the clock to USI IP w/o gating */ + if (usi->clkreq_on) { + val = readl(usi->regs + USI_OPTION); + val &= ~USI_OPTION_CLKSTOP_ON; + val |= USI_OPTION_CLKREQ_ON; + writel(val, usi->regs + USI_OPTION); + } + + clk_bulk_disable_unprepare(usi->data->num_clks, usi->clks); + + return ret; +} + +static int exynos_usi_configure(struct exynos_usi *usi) +{ + int ret; + + ret = exynos_usi_set_sw_conf(usi, usi->mode); + if (ret) + return ret; + + if (usi->data->ver == USI_VER2) + return exynos_usi_enable(usi); + + return 0; +} + +static int exynos_usi_parse_dt(struct device_node *np, struct exynos_usi *usi) +{ + int ret; + u32 mode; + + ret = of_property_read_u32(np, "samsung,mode", &mode); + if (ret) + return ret; + if (mode < usi->data->min_mode || mode > usi->data->max_mode) + return -EINVAL; + usi->mode = mode; + + usi->sysreg = syscon_regmap_lookup_by_phandle(np, "samsung,sysreg"); + if (IS_ERR(usi->sysreg)) + return PTR_ERR(usi->sysreg); + + ret = of_property_read_u32_index(np, "samsung,sysreg", 1, + &usi->sw_conf); + if (ret) + return ret; + + usi->clkreq_on = of_property_read_bool(np, "samsung,clkreq-on"); + + return 0; +} + +static int exynos_usi_get_clocks(struct exynos_usi *usi) +{ + const size_t num = usi->data->num_clks; + struct device *dev = usi->dev; + size_t i; + + if (num == 0) + return 0; + + usi->clks = devm_kcalloc(dev, num, sizeof(*usi->clks), GFP_KERNEL); + if (!usi->clks) + return -ENOMEM; + + for (i = 0; i < num; ++i) + usi->clks[i].id = usi->data->clk_names[i]; + + return devm_clk_bulk_get(dev, num, usi->clks); +} + +static int exynos_usi_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct device_node *np = dev->of_node; + struct exynos_usi *usi; + int ret; + + usi = devm_kzalloc(dev, sizeof(*usi), GFP_KERNEL); + if (!usi) + return -ENOMEM; + + usi->dev = dev; + platform_set_drvdata(pdev, usi); + + usi->data = of_device_get_match_data(dev); + if (!usi->data) + return -EINVAL; + + ret = exynos_usi_parse_dt(np, usi); + if (ret) + return ret; + + ret = exynos_usi_get_clocks(usi); + if (ret) + return ret; + + if (usi->data->ver == USI_VER2) { + usi->regs = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(usi->regs)) + return PTR_ERR(usi->regs); + } + + ret = exynos_usi_configure(usi); + if (ret) + return ret; + + /* Make it possible to embed protocol nodes into USI np */ + return of_platform_populate(np, NULL, NULL, dev); +} + +static int __maybe_unused exynos_usi_resume_noirq(struct device *dev) +{ + struct exynos_usi *usi = dev_get_drvdata(dev); + + return exynos_usi_configure(usi); +} + +static const struct dev_pm_ops exynos_usi_pm = { + SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(NULL, exynos_usi_resume_noirq) +}; + +static struct platform_driver exynos_usi_driver = { + .driver = { + .name = "exynos-usi", + .pm = &exynos_usi_pm, + .of_match_table = exynos_usi_dt_match, + }, + .probe = exynos_usi_probe, +}; +module_platform_driver(exynos_usi_driver); + +MODULE_DESCRIPTION("Samsung USI driver"); +MODULE_AUTHOR("Sam Protsenko <semen.protsenko@linaro.org>"); +MODULE_LICENSE("GPL"); |