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([2a0b:e7c0:0:107::aaaa:59]) by smtp.gmail.com with ESMTPSA id bh12-20020a05600c3d0c00b0040b2976eb02sm18178185wmb.10.2023.12.05.01.56.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Dec 2023 01:56:10 -0800 (PST) Message-ID: <2c3824d7-0960-4de7-8fae-01478fdef8fe@kernel.org> Date: Tue, 5 Dec 2023 10:56:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 7/7] tty: i3c: add TTY over I3C master support To: Frank Li , miquel.raynal@bootlin.com Cc: alexandre.belloni@bootlin.com, conor.culhane@silvaco.com, imx@lists.linux.dev, joe@perches.com, linux-i3c@lists.infradead.org, linux-kernel@vger.kernel.org, zbigniew.lukwinski@linux.intel.com, gregkh@linuxfoundation.org, linux-serial@vger.kernel.org References: <20231130224408.3591288-1-Frank.Li@nxp.com> <20231130224408.3591288-8-Frank.Li@nxp.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; keydata= xsFNBE6S54YBEACzzjLwDUbU5elY4GTg/NdotjA0jyyJtYI86wdKraekbNE0bC4zV+ryvH4j rrcDwGs6tFVrAHvdHeIdI07s1iIx5R/ndcHwt4fvI8CL5PzPmn5J+h0WERR5rFprRh6axhOk rSD5CwQl19fm4AJCS6A9GJtOoiLpWn2/IbogPc71jQVrupZYYx51rAaHZ0D2KYK/uhfc6neJ i0WqPlbtIlIrpvWxckucNu6ZwXjFY0f3qIRg3Vqh5QxPkojGsq9tXVFVLEkSVz6FoqCHrUTx wr+aw6qqQVgvT/McQtsI0S66uIkQjzPUrgAEtWUv76rM4ekqL9stHyvTGw0Fjsualwb0Gwdx ReTZzMgheAyoy/umIOKrSEpWouVoBt5FFSZUyjuDdlPPYyPav+hpI6ggmCTld3u2hyiHji2H cDpcLM2LMhlHBipu80s9anNeZhCANDhbC5E+NZmuwgzHBcan8WC7xsPXPaiZSIm7TKaVoOcL 9tE5aN3jQmIlrT7ZUX52Ff/hSdx/JKDP3YMNtt4B0cH6ejIjtqTd+Ge8sSttsnNM0CQUkXps w98jwz+Lxw/bKMr3NSnnFpUZaxwji3BC9vYyxKMAwNelBCHEgS/OAa3EJoTfuYOK6wT6nadm YqYjwYbZE5V/SwzMbpWu7Jwlvuwyfo5mh7w5iMfnZE+vHFwp/wARAQABzSFKaXJpIFNsYWJ5 IDxqaXJpc2xhYnlAa2VybmVsLm9yZz7CwXcEEwEIACEFAlW3RUwCGwMFCwkIBwIGFQgJCgsC BBYCAwECHgECF4AACgkQvSWxBAa0cEnVTg//TQpdIAr8Tn0VAeUjdVIH9XCFw+cPSU+zMSCH eCZoA/N6gitEcnvHoFVVM7b3hK2HgoFUNbmYC0RdcSc80pOF5gCnACSP9XWHGWzeKCARRcQR 4s5YD8I4VV5hqXcKo2DFAtIOVbHDW+0okOzcecdasCakUTr7s2fXz97uuoc2gIBB7bmHUGAH XQXHvdnCLjDjR+eJN+zrtbqZKYSfj89s/ZHn5Slug6w8qOPT1sVNGG+eWPlc5s7XYhT9z66E l5C0rG35JE4PhC+tl7BaE5IwjJlBMHf/cMJxNHAYoQ1hWQCKOfMDQ6bsEr++kGUCbHkrEFwD UVA72iLnnnlZCMevwE4hc0zVhseWhPc/KMYObU1sDGqaCesRLkE3tiE7X2cikmj/qH0CoMWe gjnwnQ2qVJcaPSzJ4QITvchEQ+tbuVAyvn9H+9MkdT7b7b2OaqYsUP8rn/2k1Td5zknUz7iF oJ0Z9wPTl6tDfF8phaMIPISYrhceVOIoL+rWfaikhBulZTIT5ihieY9nQOw6vhOfWkYvv0Dl o4GRnb2ybPQpfEs7WtetOsUgiUbfljTgILFw3CsPW8JESOGQc0Pv8ieznIighqPPFz9g+zSu Ss/rpcsqag5n9rQp/H3WW5zKUpeYcKGaPDp/vSUovMcjp8USIhzBBrmI7UWAtuedG9prjqfO wU0ETpLnhgEQAM+cDWLL+Wvc9cLhA2OXZ/gMmu7NbYKjfth1UyOuBd5emIO+d4RfFM02XFTI t4MxwhAryhsKQQcA4iQNldkbyeviYrPKWjLTjRXT5cD2lpWzr+Jx7mX7InV5JOz1Qq+P+nJW YIBjUKhI03ux89p58CYil24Zpyn2F5cX7U+inY8lJIBwLPBnc9Z0An/DVnUOD+0wIcYVnZAK DiIXODkGqTg3fhZwbbi+KAhtHPFM2fGw2VTUf62IHzV+eBSnamzPOBc1XsJYKRo3FHNeLuS8 f4wUe7bWb9O66PPFK/RkeqNX6akkFBf9VfrZ1rTEKAyJ2uqf1EI1olYnENk4+00IBa+BavGQ 8UW9dGW3nbPrfuOV5UUvbnsSQwj67pSdrBQqilr5N/5H9z7VCDQ0dhuJNtvDSlTf2iUFBqgk 3smln31PUYiVPrMP0V4ja0i9qtO/TB01rTfTyXTRtqz53qO5dGsYiliJO5aUmh8swVpotgK4 /57h3zGsaXO9PGgnnAdqeKVITaFTLY1ISg+Ptb4KoliiOjrBMmQUSJVtkUXMrCMCeuPDGHo7 39Xc75lcHlGuM3yEB//htKjyprbLeLf1y4xPyTeeF5zg/0ztRZNKZicgEmxyUNBHHnBKHQxz 1j+mzH0HjZZtXjGu2KLJ18G07q0fpz2ZPk2D53Ww39VNI/J9ABEBAAHCwV8EGAECAAkFAk6S 54YCGwwACgkQvSWxBAa0cEk3tRAAgO+DFpbyIa4RlnfpcW17AfnpZi9VR5+zr496n2jH/1ld wRO/S+QNSA8qdABqMb9WI4BNaoANgcg0AS429Mq0taaWKkAjkkGAT7mD1Q5PiLr06Y/+Kzdr 90eUVneqM2TUQQbK+Kh7JwmGVrRGNqQrDk+gRNvKnGwFNeTkTKtJ0P8jYd7P1gZb9Fwj9YLx jhn/sVIhNmEBLBoI7PL+9fbILqJPHgAwW35rpnq4f/EYTykbk1sa13Tav6btJ+4QOgbcezWI wZ5w/JVfEJW9JXp3BFAVzRQ5nVrrLDAJZ8Y5ioWcm99JtSIIxXxt9FJaGc1Bgsi5K/+dyTKL wLMJgiBzbVx8G+fCJJ9YtlNOPWhbKPlrQ8+AY52Aagi9WNhe6XfJdh5g6ptiOILm330mkR4g W6nEgZVyIyTq3ekOuruftWL99qpP5zi+eNrMmLRQx9iecDNgFr342R9bTDlb1TLuRb+/tJ98 f/bIWIr0cqQmqQ33FgRhrG1+Xml6UXyJ2jExmlO8JljuOGeXYh6ZkIEyzqzffzBLXZCujlYQ DFXpyMNVJ2ZwPmX2mWEoYuaBU0JN7wM+/zWgOf2zRwhEuD3A2cO2PxoiIfyUEfB9SSmffaK/ S4xXoB6wvGENZ85Hg37C7WDNdaAt6Xh2uQIly5grkgvWppkNy4ZHxE+jeNsU7tg= In-Reply-To: <20231130224408.3591288-8-Frank.Li@nxp.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231205_015613_591480_47EECFCF X-CRM114-Status: GOOD ( 32.35 ) X-BeenThere: linux-i3c@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-i3c" Errors-To: linux-i3c-bounces+linux-i3c=archiver.kernel.org@lists.infradead.org On 30. 11. 23, 23:44, Frank Li wrote: > In typical embedded Linux systems, UART consoles require at least two pins, > TX and RX. In scenarios where I2C/I3C devices like sensors or PMICs are > present, we can save these two pins by using this driver. Pins is crucial > resources, especially in small chip packages. > > This introduces support for using the I3C bus to transfer console tty data, > effectively replacing the need for dedicated UART pins. This not only > conserves valuable pin resources but also facilitates testing of I3C's > advanced features, including early termination, in-band interrupt (IBI) > support, and the creation of more complex data patterns. Additionally, > it aids in identifying and addressing issues within the I3C controller > driver. > > Signed-off-by: Frank Li ... > --- a/drivers/tty/Kconfig > +++ b/drivers/tty/Kconfig > @@ -412,6 +412,19 @@ config RPMSG_TTY > To compile this driver as a module, choose M here: the module will be > called rpmsg_tty. > > +config I3C_TTY > + tristate "TTY over I3C" > + depends on I3C > + help > + Select this options if you'd like use TTY over I3C master controller this option to use add a period to the end. > + > + This makes it possible for user-space programs to send and receive > + data as a standard tty protocol. I3C provide relatively higher data > + transfer rate and less pin numbers, SDA/SCL are shared with other > + devices. > + > + If unsure, say N > + > endif # TTY > > source "drivers/tty/serdev/Kconfig" ... > --- /dev/null > +++ b/drivers/tty/i3c_tty.c > @@ -0,0 +1,443 @@ ... > +struct ttyi3c_port { > + struct tty_port port; > + int minor; > + spinlock_t xlock; /* protect xmit */ > + char tx_buff[I3C_TTY_TRANS_SIZE]; > + char rx_buff[I3C_TTY_TRANS_SIZE]; These should be u8 as per the other changes throughout the tty layer. > + struct i3c_device *i3cdev; > + struct work_struct txwork; > + struct work_struct rxwork; > + struct completion txcomplete; > + unsigned long status; > + int buf_overrun; Can this be ever negative? > +}; > + > +struct workqueue_struct *workqueue; Is this related: Still below items not be fixed (according to Jiri Slaby's comments) - rxwork thread: need trigger from two position. - common thread queue: need some suggestion ? As I don't remember, could you elaborate again why you need your own workqueue? You need to do it in the commit log anyway. ... > +static ssize_t i3c_write(struct tty_struct *tty, const unsigned char *buf, size_t count) > +{ > + struct ttyi3c_port *sport = tty->driver_data; > + unsigned long flags; > + bool is_empty; > + int ret; > + > + spin_lock_irqsave(&sport->xlock, flags); > + ret = kfifo_in(&sport->port.xmit_fifo, buf, count); > + is_empty = kfifo_is_empty(&sport->port.xmit_fifo); > + spin_unlock_irqrestore(&sport->xlock, flags); > + > + if (!is_empty) > + queue_work(workqueue, &sport->txwork); > + > + return ret; > +} > + > +static int i3c_put_char(struct tty_struct *tty, unsigned char ch) > +{ > + struct ttyi3c_port *sport = tty->driver_data; > + unsigned long flags; > + int ret = 0; Unneeded initialization. > + > + spin_lock_irqsave(&sport->xlock, flags); > + ret = kfifo_put(&sport->port.xmit_fifo, ch); > + spin_unlock_irqrestore(&sport->xlock, flags); > + > + return ret; > +} ... > +static void tty_i3c_rxwork(struct work_struct *work) > +{ > + struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, rxwork); > + struct i3c_priv_xfer xfers; > + int retry = I3C_TTY_RETRY; Likely, should be unsigned. > + u16 status = BIT(0); > + int ret; > + > + memset(&xfers, 0, sizeof(xfers)); > + xfers.data.in = sport->rx_buff; > + xfers.len = I3C_TTY_TRANS_SIZE; > + xfers.rnw = 1; > + > + do { > + if (test_bit(I3C_TTY_RX_STOP, &sport->status)) > + break; > + > + i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1); > + > + if (xfers.actual_len) { > + ret = tty_insert_flip_string(&sport->port, sport->rx_buff, > + xfers.actual_len); > + if (ret < xfers.actual_len) > + sport->buf_overrun++; > + > + retry = I3C_TTY_RETRY; > + continue; > + } > + > + status = BIT(0); > + i3c_device_getstatus_format1(sport->i3cdev, &status); > + /* > + * Target side needs some time to fill data into fifo. Target side may not > + * have hardware update status in real time. Software update status always > + * needs some delays. > + * > + * Generally, target side have circular buffer in memory, it will be moved > + * into FIFO by CPU or DMA. 'status' just show if circular buffer empty. But > + * there are gap, especially CPU have not response irq to fill FIFO in time. > + * So xfers.actual will be zero, wait for little time to avoid flood > + * transfer in i3c bus. > + */ > + usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US); > + retry--; > + > + } while (retry && (status & BIT(0))); > + > + tty_flip_buffer_push(&sport->port); > +} > + > +static void tty_i3c_txwork(struct work_struct *work) > +{ > + struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, txwork); > + struct i3c_priv_xfer xfers; > + int retry = I3C_TTY_RETRY; Detto. > + unsigned long flags; > + int ret; > + > + xfers.rnw = 0; > + xfers.data.out = sport->tx_buff; > + > + while (!kfifo_is_empty(&sport->port.xmit_fifo) && retry) { > + xfers.len = kfifo_len(&sport->port.xmit_fifo); > + xfers.len = min_t(u16, I3C_TTY_TRANS_SIZE, xfers.len); > + > + xfers.len = kfifo_out_peek(&sport->port.xmit_fifo, sport->tx_buff, xfers.len); Can this simply be: xfers.len = kfifo_out_peek(&sport->port.xmit_fifo, sport->tx_buff, I3C_TTY_TRANS_SIZE); ? > + > + ret = i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1); > + if (ret) { > + /* > + * Target side may not move data out of FIFO. delay can't resolve problem, > + * just reduce some possiblity. Target can't end I3C SDR mode write > + * transfer, discard data is reasonable when FIFO overrun. > + */ > + usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US); > + retry--; > + } else { > + retry = I3C_TTY_RETRY; > + ret = kfifo_out(&sport->port.xmit_fifo, sport->tx_buff, xfers.len); Just to make sure: xfers.len is nor overwritten by i3c_device_do_priv_xfers(), right? > + } > + } > + > + spin_lock_irqsave(&sport->xlock, flags); Why do you take the lock here, but not during the kfifo operations above? > + if (kfifo_is_empty(&sport->port.xmit_fifo)) > + complete(&sport->txcomplete); > + spin_unlock_irqrestore(&sport->xlock, flags); > +} > +static int __init i3c_tty_init(void) > +{ > + int ret; > + > + i3c_tty_driver = tty_alloc_driver(I3C_TTY_MINORS, > + TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV); > + > + if (IS_ERR(i3c_tty_driver)) > + return PTR_ERR(i3c_tty_driver); > + > + i3c_tty_driver->driver_name = "ttyI3C"; > + i3c_tty_driver->name = "ttyI3C"; > + i3c_tty_driver->minor_start = 0, > + i3c_tty_driver->type = TTY_DRIVER_TYPE_SERIAL, > + i3c_tty_driver->subtype = SERIAL_TYPE_NORMAL, > + i3c_tty_driver->init_termios = tty_std_termios; > + i3c_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | > + CLOCAL; > + i3c_tty_driver->init_termios.c_lflag = 0; > + > + tty_set_operations(i3c_tty_driver, &i3c_tty_ops); > + > + ret = tty_register_driver(i3c_tty_driver); > + if (ret) > + goto err_tty_register_driver; > + > + ret = i3c_driver_register(&i3c_driver); > + if (ret) > + goto err_i3c_driver_register; > + > + workqueue = alloc_workqueue("ttyI3C", 0, 0); Can it happen that you already queue something on this wq, while not allocated yet? I mean: should this be done first in i3c_tty_init()? > + if (!workqueue) { > + ret = PTR_ERR(workqueue); > + goto err_alloc_workqueue; > + } > + > + return 0; > + > +err_alloc_workqueue: > + i3c_driver_unregister(&i3c_driver); > + > +err_i3c_driver_register: > + tty_unregister_driver(i3c_tty_driver); > + > +err_tty_register_driver: > + tty_driver_kref_put(i3c_tty_driver); > + > + return ret; > +} > + > +static void __exit i3c_tty_exit(void) > +{ > + i3c_driver_unregister(&i3c_driver); > + tty_unregister_driver(i3c_tty_driver); > + tty_driver_kref_put(i3c_tty_driver); > + idr_destroy(&i3c_tty_minors); What about the wq? > +} regards, -- js suse labs -- linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c