From 5b143d2a6edeae59700420c948f7d793da3356a8 Mon Sep 17 00:00:00 2001 From: Sebastien Bourdelin Date: Wed, 1 Nov 2017 13:14:33 -0400 Subject: [PATCH] bus: add driver for the Technologic Systems NBUS This driver implements a GPIOs bit-banged bus, called the NBUS by Technologic Systems. It is used to communicate with the peripherals in the FPGA on the TS-4600 SoM. Signed-off-by: Sebastien Bourdelin Acked-by: Linus Walleij Signed-off-by: Arnd Bergmann --- drivers/bus/Kconfig | 8 ++ drivers/bus/Makefile | 1 + drivers/bus/ts-nbus.c | 375 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/ts-nbus.h | 18 +++ 4 files changed, 402 insertions(+) create mode 100644 drivers/bus/ts-nbus.c create mode 100644 include/linux/ts-nbus.h diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig index ae3d8f3..854348e 100644 --- a/drivers/bus/Kconfig +++ b/drivers/bus/Kconfig @@ -157,6 +157,14 @@ config TEGRA_GMI Driver for the Tegra Generic Memory Interface bus which can be used to attach devices such as NOR, UART, FPGA and more. +config TS_NBUS + tristate "Technologic Systems NBUS Driver" + depends on SOC_IMX28 + depends on OF_GPIO && PWM + help + Driver for the Technologic Systems NBUS which is used to interface + with the peripherals in the FPGA of the TS-4600 SoM. + config UNIPHIER_SYSTEM_BUS tristate "UniPhier System Bus driver" depends on ARCH_UNIPHIER && OF diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile index cc6364b..72377f7 100644 --- a/drivers/bus/Makefile +++ b/drivers/bus/Makefile @@ -20,6 +20,7 @@ obj-$(CONFIG_SUNXI_RSB) += sunxi-rsb.o obj-$(CONFIG_SIMPLE_PM_BUS) += simple-pm-bus.o obj-$(CONFIG_TEGRA_ACONNECT) += tegra-aconnect.o obj-$(CONFIG_TEGRA_GMI) += tegra-gmi.o +obj-$(CONFIG_TS_NBUS) += ts-nbus.o obj-$(CONFIG_UNIPHIER_SYSTEM_BUS) += uniphier-system-bus.o obj-$(CONFIG_VEXPRESS_CONFIG) += vexpress-config.o diff --git a/drivers/bus/ts-nbus.c b/drivers/bus/ts-nbus.c new file mode 100644 index 0000000..073fd90 --- /dev/null +++ b/drivers/bus/ts-nbus.c @@ -0,0 +1,375 @@ +/* + * NBUS driver for TS-4600 based boards + * + * Copyright (c) 2016 - Savoir-faire Linux + * Author: Sebastien Bourdelin + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + * + * This driver implements a GPIOs bit-banged bus, called the NBUS by Technologic + * Systems. It is used to communicate with the peripherals in the FPGA on the + * TS-4600 SoM. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define TS_NBUS_DIRECTION_IN 0 +#define TS_NBUS_DIRECTION_OUT 1 +#define TS_NBUS_WRITE_ADR 0 +#define TS_NBUS_WRITE_VAL 1 + +struct ts_nbus { + struct pwm_device *pwm; + struct gpio_descs *data; + struct gpio_desc *csn; + struct gpio_desc *txrx; + struct gpio_desc *strobe; + struct gpio_desc *ale; + struct gpio_desc *rdy; + struct mutex lock; +}; + +/* + * request all gpios required by the bus. + */ +static int ts_nbus_init_pdata(struct platform_device *pdev, struct ts_nbus + *ts_nbus) +{ + ts_nbus->data = devm_gpiod_get_array(&pdev->dev, "ts,data", + GPIOD_OUT_HIGH); + if (IS_ERR(ts_nbus->data)) { + dev_err(&pdev->dev, "failed to retrieve ts,data-gpio from dts\n"); + return PTR_ERR(ts_nbus->data); + } + + ts_nbus->csn = devm_gpiod_get(&pdev->dev, "ts,csn", GPIOD_OUT_HIGH); + if (IS_ERR(ts_nbus->csn)) { + dev_err(&pdev->dev, "failed to retrieve ts,csn-gpio from dts\n"); + return PTR_ERR(ts_nbus->csn); + } + + ts_nbus->txrx = devm_gpiod_get(&pdev->dev, "ts,txrx", GPIOD_OUT_HIGH); + if (IS_ERR(ts_nbus->txrx)) { + dev_err(&pdev->dev, "failed to retrieve ts,txrx-gpio from dts\n"); + return PTR_ERR(ts_nbus->txrx); + } + + ts_nbus->strobe = devm_gpiod_get(&pdev->dev, "ts,strobe", GPIOD_OUT_HIGH); + if (IS_ERR(ts_nbus->strobe)) { + dev_err(&pdev->dev, "failed to retrieve ts,strobe-gpio from dts\n"); + return PTR_ERR(ts_nbus->strobe); + } + + ts_nbus->ale = devm_gpiod_get(&pdev->dev, "ts,ale", GPIOD_OUT_HIGH); + if (IS_ERR(ts_nbus->ale)) { + dev_err(&pdev->dev, "failed to retrieve ts,ale-gpio from dts\n"); + return PTR_ERR(ts_nbus->ale); + } + + ts_nbus->rdy = devm_gpiod_get(&pdev->dev, "ts,rdy", GPIOD_IN); + if (IS_ERR(ts_nbus->rdy)) { + dev_err(&pdev->dev, "failed to retrieve ts,rdy-gpio from dts\n"); + return PTR_ERR(ts_nbus->rdy); + } + + return 0; +} + +/* + * the data gpios are used for reading and writing values, their directions + * should be adjusted accordingly. + */ +static void ts_nbus_set_direction(struct ts_nbus *ts_nbus, int direction) +{ + int i; + + for (i = 0; i < 8; i++) { + if (direction == TS_NBUS_DIRECTION_IN) + gpiod_direction_input(ts_nbus->data->desc[i]); + else + /* when used as output the default state of the data + * lines are set to high */ + gpiod_direction_output(ts_nbus->data->desc[i], 1); + } +} + +/* + * reset the bus in its initial state. + * The data, csn, strobe and ale lines must be zero'ed to let the FPGA knows a + * new transaction can be process. + */ +static void ts_nbus_reset_bus(struct ts_nbus *ts_nbus) +{ + int i; + int values[8]; + + for (i = 0; i < 8; i++) + values[i] = 0; + + gpiod_set_array_value_cansleep(8, ts_nbus->data->desc, values); + gpiod_set_value_cansleep(ts_nbus->csn, 0); + gpiod_set_value_cansleep(ts_nbus->strobe, 0); + gpiod_set_value_cansleep(ts_nbus->ale, 0); +} + +/* + * let the FPGA knows it can process. + */ +static void ts_nbus_start_transaction(struct ts_nbus *ts_nbus) +{ + gpiod_set_value_cansleep(ts_nbus->strobe, 1); +} + +/* + * read a byte value from the data gpios. + * return 0 on success or negative errno on failure. + */ +static int ts_nbus_read_byte(struct ts_nbus *ts_nbus, u8 *val) +{ + struct gpio_descs *gpios = ts_nbus->data; + int ret, i; + + *val = 0; + for (i = 0; i < 8; i++) { + ret = gpiod_get_value_cansleep(gpios->desc[i]); + if (ret < 0) + return ret; + if (ret) + *val |= BIT(i); + } + + return 0; +} + +/* + * set the data gpios accordingly to the byte value. + */ +static void ts_nbus_write_byte(struct ts_nbus *ts_nbus, u8 byte) +{ + struct gpio_descs *gpios = ts_nbus->data; + int i; + int values[8]; + + for (i = 0; i < 8; i++) + if (byte & BIT(i)) + values[i] = 1; + else + values[i] = 0; + + gpiod_set_array_value_cansleep(8, gpios->desc, values); +} + +/* + * reading the bus consists of resetting the bus, then notifying the FPGA to + * send the data in the data gpios and return the read value. + * return 0 on success or negative errno on failure. + */ +static int ts_nbus_read_bus(struct ts_nbus *ts_nbus, u8 *val) +{ + ts_nbus_reset_bus(ts_nbus); + ts_nbus_start_transaction(ts_nbus); + + return ts_nbus_read_byte(ts_nbus, val); +} + +/* + * writing to the bus consists of resetting the bus, then define the type of + * command (address/value), write the data and notify the FPGA to retrieve the + * value in the data gpios. + */ +static void ts_nbus_write_bus(struct ts_nbus *ts_nbus, int cmd, u8 val) +{ + ts_nbus_reset_bus(ts_nbus); + + if (cmd == TS_NBUS_WRITE_ADR) + gpiod_set_value_cansleep(ts_nbus->ale, 1); + + ts_nbus_write_byte(ts_nbus, val); + ts_nbus_start_transaction(ts_nbus); +} + +/* + * read the value in the FPGA register at the given address. + * return 0 on success or negative errno on failure. + */ +int ts_nbus_read(struct ts_nbus *ts_nbus, u8 adr, u16 *val) +{ + int ret, i; + u8 byte; + + /* bus access must be atomic */ + mutex_lock(&ts_nbus->lock); + + /* set the bus in read mode */ + gpiod_set_value_cansleep(ts_nbus->txrx, 0); + + /* write address */ + ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_ADR, adr); + + /* set the data gpios direction as input before reading */ + ts_nbus_set_direction(ts_nbus, TS_NBUS_DIRECTION_IN); + + /* reading value MSB first */ + do { + *val = 0; + byte = 0; + for (i = 1; i >= 0; i--) { + /* read a byte from the bus, leave on error */ + ret = ts_nbus_read_bus(ts_nbus, &byte); + if (ret < 0) + goto err; + + /* append the byte read to the final value */ + *val |= byte << (i * 8); + } + gpiod_set_value_cansleep(ts_nbus->csn, 1); + ret = gpiod_get_value_cansleep(ts_nbus->rdy); + } while (ret); + +err: + /* restore the data gpios direction as output after reading */ + ts_nbus_set_direction(ts_nbus, TS_NBUS_DIRECTION_OUT); + + mutex_unlock(&ts_nbus->lock); + + return ret; +} +EXPORT_SYMBOL_GPL(ts_nbus_read); + +/* + * write the desired value in the FPGA register at the given address. + */ +int ts_nbus_write(struct ts_nbus *ts_nbus, u8 adr, u16 val) +{ + int i; + + /* bus access must be atomic */ + mutex_lock(&ts_nbus->lock); + + /* set the bus in write mode */ + gpiod_set_value_cansleep(ts_nbus->txrx, 1); + + /* write address */ + ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_ADR, adr); + + /* writing value MSB first */ + for (i = 1; i >= 0; i--) + ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_VAL, (u8)(val >> (i * 8))); + + /* wait for completion */ + gpiod_set_value_cansleep(ts_nbus->csn, 1); + while (gpiod_get_value_cansleep(ts_nbus->rdy) != 0) { + gpiod_set_value_cansleep(ts_nbus->csn, 0); + gpiod_set_value_cansleep(ts_nbus->csn, 1); + } + + mutex_unlock(&ts_nbus->lock); + + return 0; +} +EXPORT_SYMBOL_GPL(ts_nbus_write); + +static int ts_nbus_probe(struct platform_device *pdev) +{ + struct pwm_device *pwm; + struct pwm_args pargs; + struct device *dev = &pdev->dev; + struct ts_nbus *ts_nbus; + int ret; + + ts_nbus = devm_kzalloc(dev, sizeof(*ts_nbus), GFP_KERNEL); + if (!ts_nbus) + return -ENOMEM; + + mutex_init(&ts_nbus->lock); + + ret = ts_nbus_init_pdata(pdev, ts_nbus); + if (ret < 0) + return ret; + + pwm = devm_pwm_get(dev, NULL); + if (IS_ERR(pwm)) { + ret = PTR_ERR(pwm); + if (ret != -EPROBE_DEFER) + dev_err(dev, "unable to request PWM\n"); + return ret; + } + + pwm_get_args(pwm, &pargs); + if (!pargs.period) { + dev_err(&pdev->dev, "invalid PWM period\n"); + return -EINVAL; + } + + /* + * FIXME: pwm_apply_args() should be removed when switching to + * the atomic PWM API. + */ + pwm_apply_args(pwm); + ret = pwm_config(pwm, pargs.period, pargs.period); + if (ret < 0) + return ret; + + /* + * we can now start the FPGA and populate the peripherals. + */ + pwm_enable(pwm); + ts_nbus->pwm = pwm; + + /* + * let the child nodes retrieve this instance of the ts-nbus. + */ + dev_set_drvdata(dev, ts_nbus); + + ret = of_platform_populate(dev->of_node, NULL, NULL, dev); + if (ret < 0) + return ret; + + dev_info(dev, "initialized\n"); + + return 0; +} + +static int ts_nbus_remove(struct platform_device *pdev) +{ + struct ts_nbus *ts_nbus = dev_get_drvdata(&pdev->dev); + + /* shutdown the FPGA */ + mutex_lock(&ts_nbus->lock); + pwm_disable(ts_nbus->pwm); + mutex_unlock(&ts_nbus->lock); + + return 0; +} + +static const struct of_device_id ts_nbus_of_match[] = { + { .compatible = "technologic,ts-nbus", }, + { }, +}; +MODULE_DEVICE_TABLE(of, ts_nbus_of_match); + +static struct platform_driver ts_nbus_driver = { + .probe = ts_nbus_probe, + .remove = ts_nbus_remove, + .driver = { + .name = "ts_nbus", + .of_match_table = ts_nbus_of_match, + }, +}; + +module_platform_driver(ts_nbus_driver); + +MODULE_ALIAS("platform:ts_nbus"); +MODULE_AUTHOR("Sebastien Bourdelin "); +MODULE_DESCRIPTION("Technologic Systems NBUS"); +MODULE_LICENSE("GPL v2"); diff --git a/include/linux/ts-nbus.h b/include/linux/ts-nbus.h new file mode 100644 index 0000000..5bd4c82 --- /dev/null +++ b/include/linux/ts-nbus.h @@ -0,0 +1,18 @@ +/* + * Copyright (c) 2016 - Savoir-faire Linux + * Author: Sebastien Bourdelin + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#ifndef _TS_NBUS_H +#define _TS_NBUS_H + +struct ts_nbus; + +extern int ts_nbus_read(struct ts_nbus *ts_nbus, u8 adr, u16 *val); +extern int ts_nbus_write(struct ts_nbus *ts_nbus, u8 adr, u16 val); + +#endif /* _TS_NBUS_H */ -- 2.7.4