From patchwork Thu Jan 25 10:00:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rengarajan S X-Patchwork-Id: 766293 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.153.233]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F28C71C686; Thu, 25 Jan 2024 10:02:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=68.232.153.233 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706176949; cv=none; b=GcHimR7tXEasaTWUOxaJ5NUVLYQXqGOdpXDZ1J9Xeg466YDM12q8PYsGLzgT7aqLYLknuUJ9nekO/STpUfK78N+MUWyxzucHGq9bv/ILUibfLxtfTQSgo3xHzqLPe4upb55qr1oiT4F4bnSUsg0lB7+dhXsEAYGdf8XytJOSAoc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706176949; c=relaxed/simple; bh=Tv1+9k+cs9ODrgYL0DhM6PbCDNkcFvwIQHm8qIIPFOw=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=pHqX3409f/4AvmVqyV8jipOnFkTOw2dP3nRRha7iAfzGXYV9x1RCZOmKQbb0ISUZ+hHlSC+0ivFF2bIVpLnaEBb5awGlGQyi8pLQf1gvsAio7bc6yB+hhkBozuhrTq1vN5OtrFoQtW7CTXS/JGLgUnnpQnuoRlVcx1kwheMX8cE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=microchip.com; spf=pass smtp.mailfrom=microchip.com; dkim=pass (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b=VvEyrU92; arc=none smtp.client-ip=68.232.153.233 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=microchip.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=microchip.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b="VvEyrU92" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1706176948; x=1737712948; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=Tv1+9k+cs9ODrgYL0DhM6PbCDNkcFvwIQHm8qIIPFOw=; b=VvEyrU92g4QY0st1jN98VMuuShbvLKQy/YQAEsT6yP4XLhZ0pWBhQBJd zhge5HH6Vac+PCMmOK1bxgyAJQN5vS7xM+G+kZz3oUIfP0YwtlmhPsSn7 lUVdckmnVfBX5VLPv2TQsoercLw6UxxmPAwtN8611ykrB/APVSM8GyFMs 3zTUQuvVhLMmyHccxWtxugkv7KsDo5pPxFyrqCj+7KQvLxxmWrX4/JFQl 7mTjuGbymJ31VJD9+lb31+xb90+WYmL9TAX3CXB3aKkdZjkHPDjnhtnMf 583N22J5dQTWClrELdQCjxx52X+FsFrAGBOzvPZFWdyQQlGrkCFVvlS7h w==; X-CSE-ConnectionGUID: EcHPnxniQdWGuWl+Gd9iBA== X-CSE-MsgGUID: cPjp1T7gRbWSaY+EDV2BEQ== X-IronPort-AV: E=Sophos;i="6.05,216,1701154800"; d="scan'208";a="245997251" X-Amp-Result: SKIPPED(no attachment in message) Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa5.microchip.iphmx.com with ESMTP/TLS/ECDHE-RSA-AES128-GCM-SHA256; 25 Jan 2024 03:02:21 -0700 Received: from chn-vm-ex02.mchp-main.com (10.10.87.72) by chn-vm-ex02.mchp-main.com (10.10.87.72) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Thu, 25 Jan 2024 03:01:56 -0700 Received: from che-dk-ungapp03lx.microchip.com (10.10.85.11) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server id 15.1.2507.35 via Frontend Transport; Thu, 25 Jan 2024 03:01:53 -0700 From: Rengarajan S To: , , , , , CC: Subject: [PATCH v1 tty] 8250: microchip: pci1xxxx: Add Burst mode transmission support in uart driver for reading from FIFO Date: Thu, 25 Jan 2024 15:30:06 +0530 Message-ID: <20240125100006.153342-1-rengarajan.s@microchip.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 pci1xxxx_handle_irq reads the burst status and checks if the FIFO is empty and is ready to accept the incoming data. The handling is done in pci1xxxx_tx_burst where each transaction processes data in block of DWORDs, while any remaining bytes are processed individually, one byte at a time. Signed-off-by: Rengarajan S --- drivers/tty/serial/8250/8250_pci1xxxx.c | 106 ++++++++++++++++++++++++ 1 file changed, 106 insertions(+) diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c index 558c4c7f3104..d53605bf908d 100644 --- a/drivers/tty/serial/8250/8250_pci1xxxx.c +++ b/drivers/tty/serial/8250/8250_pci1xxxx.c @@ -67,6 +67,7 @@ #define SYSLOCK_RETRY_CNT 1000 #define UART_RX_BYTE_FIFO 0x00 +#define UART_TX_BYTE_FIFO 0x00 #define UART_FIFO_CTL 0x02 #define UART_ACTV_REG 0x11 @@ -100,6 +101,7 @@ #define UART_RESET_D3_RESET_DISABLE BIT(16) #define UART_BURST_STATUS_REG 0x9C +#define UART_TX_BURST_FIFO 0xA0 #define UART_RX_BURST_FIFO 0xA4 #define MAX_PORTS 4 @@ -109,6 +111,7 @@ #define UART_BURST_SIZE 4 #define UART_BST_STAT_RX_COUNT_MASK 0x00FF +#define UART_BST_STAT_TX_COUNT_MASK 0xFF00 #define UART_BST_STAT_IIR_INT_PEND 0x100000 #define UART_LSR_OVERRUN_ERR_CLR 0x43 #define UART_BST_STAT_LSR_RX_MASK 0x9F000000 @@ -116,6 +119,7 @@ #define UART_BST_STAT_LSR_OVERRUN_ERR 0x2000000 #define UART_BST_STAT_LSR_PARITY_ERR 0x4000000 #define UART_BST_STAT_LSR_FRAME_ERR 0x8000000 +#define UART_BST_STAT_LSR_THRE 0x20000000 struct pci1xxxx_8250 { unsigned int nr; @@ -344,6 +348,105 @@ static void pci1xxxx_rx_burst(struct uart_port *port, u32 uart_status) } } +static void pci1xxxx_process_write_data(struct uart_port *port, + struct circ_buf *xmit, + int *data_empty_count, + u32 *valid_byte_count) +{ + u32 valid_burst_count = *valid_byte_count / UART_BURST_SIZE; + + /* + * Each transaction transfers data in DWORDs. If there are less than + * four remaining valid_byte_count to transfer or if the circular + * buffer has insufficient space for a DWORD, the data is transferred + * one byte at a time. + */ + while (valid_burst_count) { + if (*data_empty_count - UART_BURST_SIZE < 0) + break; + if (xmit->tail > (UART_XMIT_SIZE - UART_BURST_SIZE)) + break; + writel(*(unsigned int *)&xmit->buf[xmit->tail], + port->membase + UART_TX_BURST_FIFO); + *valid_byte_count -= UART_BURST_SIZE; + *data_empty_count -= UART_BURST_SIZE; + valid_burst_count -= UART_BYTE_SIZE; + + xmit->tail = (xmit->tail + UART_BURST_SIZE) & + (UART_XMIT_SIZE - 1); + } + + while (*valid_byte_count) { + if (*data_empty_count - UART_BYTE_SIZE < 0) + break; + writeb(xmit->buf[xmit->tail], port->membase + + UART_TX_BYTE_FIFO); + *data_empty_count -= UART_BYTE_SIZE; + *valid_byte_count -= UART_BYTE_SIZE; + + /* + * When the tail of the circular buffer is reached, the next + * byte is transferred to the beginning of the buffer. + */ + xmit->tail = (xmit->tail + UART_BYTE_SIZE) & + (UART_XMIT_SIZE - 1); + + /* + * If there are any pending burst count, data is handled by + * transmitting DWORDs at a time. + */ + if (valid_burst_count && (xmit->tail < + (UART_XMIT_SIZE - UART_BURST_SIZE))) + break; + } +} + +static void pci1xxxx_tx_burst(struct uart_port *port, u32 uart_status) +{ + struct uart_8250_port *up = up_to_u8250p(port); + u32 valid_byte_count; + int data_empty_count; + struct circ_buf *xmit; + + xmit = &port->state->xmit; + + if (port->x_char) { + writeb(port->x_char, port->membase + UART_TX); + port->icount.tx++; + port->x_char = 0; + return; + } + + if ((uart_tx_stopped(port)) || (uart_circ_empty(xmit))) { + port->ops->stop_tx(port); + } else { + data_empty_count = (pci1xxxx_read_burst_status(port) & + UART_BST_STAT_TX_COUNT_MASK) >> 8; + do { + valid_byte_count = uart_circ_chars_pending(xmit); + + pci1xxxx_process_write_data(port, xmit, + &data_empty_count, + &valid_byte_count); + + port->icount.tx++; + if (uart_circ_empty(xmit)) + break; + } while (data_empty_count && valid_byte_count); + } + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(port); + + /* + * With RPM enabled, we have to wait until the FIFO is empty before + * the HW can go idle. So we get here once again with empty FIFO and + * disable the interrupt and RPM in __stop_tx() + */ + if (uart_circ_empty(xmit) && !(up->capabilities & UART_CAP_RPM)) + port->ops->stop_tx(port); +} + static int pci1xxxx_handle_irq(struct uart_port *port) { unsigned long flags; @@ -359,6 +462,9 @@ static int pci1xxxx_handle_irq(struct uart_port *port) if (status & UART_BST_STAT_LSR_RX_MASK) pci1xxxx_rx_burst(port, status); + if (status & UART_BST_STAT_LSR_THRE) + pci1xxxx_tx_burst(port, status); + spin_unlock_irqrestore(&port->lock, flags); return 1;