On 06. 01. 24, 17:02, Christoph Winklhofer via B4 Relay wrote:
From: Christoph Winklhofer <cj.winklhofer@xxxxxxxxx> Add a UART 1-Wire bus driver. The driver utilizes the UART interface via the Serial Device Bus to create the 1-Wire timing patterns. The driver was tested on a "Raspberry Pi 3B" with a DS18B20 and on a "Variscite DART-6UL" with a DS18S20 temperature sensor. The 1-Wire timing pattern and the corresponding UART baud-rate with the interpretation of the transferred bytes are described in the document: Link: https://www.analog.com/en/technical-articles/using-a-uart-to-implement-a-1wire-bus-master.html In short, the UART peripheral must support full-duplex and operate in open-drain mode. The timing patterns are generated by a specific combination of baud-rate and transmitted byte, which corresponds to a 1-Wire read bit, write bit or reset.
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--- /dev/null +++ b/drivers/w1/masters/w1-uart.c @@ -0,0 +1,398 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * w1-uart - UART 1-Wire bus driver + * + * Uses the UART interface (via Serial Device Bus) to create the 1-Wire + * timing patterns. Implements the following 1-Wire master interface: + * + * - reset_bus: requests baud-rate 9600 + * + * - touch_bit: requests baud-rate 115200 + * + * Author: Christoph Winklhofer <cj.winklhofer@xxxxxxxxx> + */ + +#include <linux/completion.h> +#include <linux/delay.h> +#include <linux/jiffies.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/of.h> +#include <linux/serdev.h> +#include <linux/w1.h> + +#define W1_UART_TIMEOUT msecs_to_jiffies(500) + +/* + * struct w1_uart_config - configuration for 1-Wire operation + * + * @baudrate: baud-rate returned from serdev + * @delay_us: delay to complete a 1-Wire cycle (in us) + * @tx_byte: byte to generate 1-Wire timing pattern + */ +struct w1_uart_config { + unsigned int baudrate; + unsigned int delay_us; + unsigned char tx_byte;
If it is a "byte", it should be u8.
+}; + +struct w1_uart_device { + struct serdev_device *serdev; + struct w1_bus_master bus; + + struct w1_uart_config cfg_reset; + struct w1_uart_config cfg_touch_0; + struct w1_uart_config cfg_touch_1; + + struct completion rx_byte_received; + unsigned char rx_byte;
The same here.
+ int rx_err; + + struct mutex mutex; +}; + +/* + * struct w1_uart_limits - limits for 1-Wire operations + * + * @baudrate: Requested baud-rate to create 1-Wire timing pattern + * @bit_min_us: minimum time for a bit (in us) + * @bit_max_us: maximum time for a bit (in us) + * @sample_us: timespan to sample 1-Wire response + * @cycle_us: duration of the 1-Wire cycle + */ +struct w1_uart_limits { + unsigned int baudrate; + unsigned int bit_min_us; + unsigned int bit_max_us; + unsigned int sample_us; + unsigned int cycle_us; +}; + +static inline unsigned int baud_to_bit_ns(unsigned int baud) +{ + return 1000000000 / baud;
NSEC_PER_SEC
+} + +static inline unsigned int to_ns(unsigned int us) +{ + return us * 1000;
NSEC_PER_USEC
+} + +/* + * Set baud-rate, delay and tx-byte to create a 1-Wire pulse and adapt + * the tx-byte according to the actual baud-rate. + * + * Reject when: + * - time for a bit outside min/max range + * - a 1-Wire response is not detectable for sent byte + */ +static int w1_uart_set_config(struct serdev_device *serdev, + const struct w1_uart_limits *limits, + struct w1_uart_config *w1cfg) +{ + unsigned int bits_low; + unsigned int bit_ns; + unsigned int low_ns; + + w1cfg->baudrate = serdev_device_set_baudrate(serdev, limits->baudrate); + if (w1cfg->baudrate == 0) + return -EINVAL; + + /* Compute in nanoseconds for accuracy */ + bit_ns = baud_to_bit_ns(w1cfg->baudrate); + bits_low = to_ns(limits->bit_min_us) / bit_ns; + /* start bit is always low */ + low_ns = bit_ns * (bits_low + 1); + + if (low_ns < to_ns(limits->bit_min_us)) + return -EINVAL; + + if (low_ns > to_ns(limits->bit_max_us)) + return -EINVAL; + + /* 1-Wire response detectable for sent byte */ + if (limits->sample_us > 0 && + bit_ns * 8 < low_ns + to_ns(limits->sample_us))
BITS_PER_BYTE
+ return -EINVAL; + + /* delay to complete 1-Wire cycle, include start and stop-bit */ + w1cfg->delay_us = 0; + if (bit_ns * 10 < to_ns(limits->cycle_us))
What is this 10? Dub it.
+ w1cfg->delay_us = + (to_ns(limits->cycle_us) - bit_ns * 10) / 1000;
And this 10? The end: / NSEC_PER_USEC
+ + /* byte to create 1-Wire pulse */ + w1cfg->tx_byte = 0xff << bits_low; + + return 0; +}
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+static int w1_uart_serdev_tx_rx(struct w1_uart_device *w1dev, + const struct w1_uart_config *w1cfg, + unsigned char *rx_byte)
u8 *
+{
...
+} + +static int w1_uart_serdev_receive_buf(struct serdev_device *serdev, + const unsigned char *buf, size_t count)
serdev already uses u8 * here. You are basing on the top of some old tree. regards, -- js suse labs