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Message-ID: <20250513215934.933807-4-jm@ti.com>
Date: Tue, 13 May 2025 16:59:30 -0500
From: Judith Mendez <jm@...com>
To: Judith Mendez <jm@...com>,
Greg Kroah-Hartman
<gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>
CC: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, Nishanth Menon <nm@...com>,
Santosh
Shilimkar <ssantosh@...nel.org>,
Vignesh Raghavendra <vigneshr@...com>,
Tero
Kristo <kristo@...nel.org>, Bin Liu <b-liu@...com>,
Andy Shevchenko
<andriy.shevchenko@...ux.intel.com>,
Andrew Davis <afd@...com>, <linux-kernel@...r.kernel.org>,
<linux-serial@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH 3/7] serial: 8250: Add PRUSS UART driver
From: Bin Liu <b-liu@...com>
This adds a new serial 8250 driver that supports the UART in PRUSS or
PRU_ICSS*.
The UART sub-module is based on the industry standard TL16C550 UART
controller, which has 16-bytes FIFO and supports 16x and 13x over
samplings.
Signed-off-by: Bin Liu <b-liu@...com>
Signed-off-by: Judith Mendez <jm@...com>
---
drivers/tty/serial/8250/8250_pruss.c | 178 +++++++++++++++++++++++++++
drivers/tty/serial/8250/Kconfig | 11 ++
drivers/tty/serial/8250/Makefile | 1 +
3 files changed, 190 insertions(+)
create mode 100644 drivers/tty/serial/8250/8250_pruss.c
diff --git a/drivers/tty/serial/8250/8250_pruss.c b/drivers/tty/serial/8250/8250_pruss.c
new file mode 100644
index 000000000000..04a455580022
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_pruss.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Serial Port driver for PRUSS UART on TI platforms
+ *
+ * Copyright (C) 2025 by Texas Instruments Incorporated - http://www.ti.com/
+ * Author: Bin Liu <b-liu@...com>
+ */
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/serial_reg.h>
+#include <linux/serial_core.h>
+
+#include "8250.h"
+
+/* PowerManagement and Emulation */
+#define PRUSS_UART_PEREMU_MGMT 12
+#define PRUSS_UART_TX_EN BIT(14)
+#define PRUSS_UART_RX_EN BIT(13)
+#define PRUSS_UART_FREE_RUN BIT(0)
+
+/* Oversampling Mode Select */
+#define PRUSS_UART_MDR 13
+#define PRUSS_UART_MDR_OSM_SEL_MASK BIT(0)
+#define PRUSS_UART_MDR_16X_MODE 0
+#define PRUSS_UART_MDR_13X_MODE 1
+
+struct pruss8250_data {
+ struct clk *clk;
+ int line;
+};
+
+static int pruss8250_startup(struct uart_port *port)
+{
+ int ret;
+
+ port->serial_out(port, PRUSS_UART_PEREMU_MGMT, 0);
+
+ ret = serial8250_do_startup(port);
+ if (!ret)
+ port->serial_out(port, PRUSS_UART_PEREMU_MGMT, PRUSS_UART_TX_EN |
+ PRUSS_UART_RX_EN |
+ PRUSS_UART_FREE_RUN);
+
+ return ret;
+}
+
+static unsigned int pruss8250_get_divisor(struct uart_port *port,
+ unsigned int baud,
+ unsigned int *frac)
+{
+ unsigned int uartclk = port->uartclk;
+ unsigned int div_13, div_16;
+ unsigned int abs_d13, abs_d16;
+ u16 quot;
+
+ div_13 = DIV_ROUND_CLOSEST(uartclk, 13 * baud);
+ div_16 = DIV_ROUND_CLOSEST(uartclk, 16 * baud);
+ div_13 = div_13 ? : 1;
+ div_16 = div_16 ? : 1;
+
+ abs_d13 = abs(baud - uartclk / 13 / div_13);
+ abs_d16 = abs(baud - uartclk / 16 / div_16);
+
+ if (abs_d13 >= abs_d16) {
+ *frac = PRUSS_UART_MDR_16X_MODE;
+ quot = div_16;
+ } else {
+ *frac = PRUSS_UART_MDR_13X_MODE;
+ quot = div_13;
+ }
+
+ return quot;
+}
+
+static void pruss8250_set_divisor(struct uart_port *port, unsigned int baud,
+ unsigned int quot, unsigned int quot_frac)
+{
+ serial8250_do_set_divisor(port, baud, quot);
+
+ /*
+ * quot_frac holds the MDR over-sampling mode
+ * which is set in pruss8250_get_divisor()
+ */
+ quot_frac &= PRUSS_UART_MDR_OSM_SEL_MASK;
+ port->serial_out(port, PRUSS_UART_MDR, quot_frac);
+}
+
+static int pruss8250_probe(struct platform_device *pdev)
+{
+ struct uart_8250_port port8250;
+ struct uart_port *port = &port8250.port;
+ struct device *dev = &pdev->dev;
+ struct pruss8250_data *data;
+ struct resource *res;
+ int ret;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ memset(&port8250, 0, sizeof(port8250));
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "Failed to get resource");
+ return -EINVAL;
+ }
+
+ if (!port->uartclk) {
+ data->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(data->clk)) {
+ dev_err(dev, "Failed to get clock!\n");
+ return -ENODEV;
+ } else {
+ port->uartclk = clk_get_rate(data->clk);
+ devm_clk_put(dev, data->clk);
+ }
+ }
+
+ port->dev = dev;
+ port->mapbase = res->start;
+ port->mapsize = resource_size(res);
+ port->type = PORT_16550A;
+ port->flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_FIXED_TYPE |
+ UPF_IOREMAP;
+ port->startup = pruss8250_startup;
+ port->rs485_config = serial8250_em485_config;
+ port->get_divisor = pruss8250_get_divisor;
+ port->set_divisor = pruss8250_set_divisor;
+
+ ret = uart_read_port_properties(port);
+ if (ret)
+ return ret;
+
+ port->iotype = UPIO_MEM32;
+ port->regshift = 2;
+
+ spin_lock_init(&port8250.port.lock);
+ port8250.capabilities = UART_CAP_FIFO | UART_CAP_AFE;
+
+ ret = serial8250_register_8250_port(&port8250);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "Unable to register 8250 port.\n");
+
+ data->line = ret;
+ platform_set_drvdata(pdev, data);
+ return 0;
+}
+
+static void pruss8250_remove(struct platform_device *pdev)
+{
+ struct pruss8250_data *data = platform_get_drvdata(pdev);
+
+ serial8250_unregister_port(data->line);
+}
+
+static const struct of_device_id pruss8250_of_match[] = {
+ { .compatible = "ti,pruss-uart", .data = (void *)PORT_16550A },
+ { /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pruss8250_of_match);
+
+static struct platform_driver pruss8250_driver = {
+ .driver = {
+ .name = "pruss8250",
+ .of_match_table = pruss8250_of_match,
+ },
+ .probe = pruss8250_probe,
+ .remove = pruss8250_remove,
+};
+
+module_platform_driver(pruss8250_driver);
+
+MODULE_AUTHOR("Bin Liu <b-liu@...com");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Serial Port driver for PRUSS UART on TI platforms");
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index f64ef0819cd4..5fdb502b7eae 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -582,6 +582,17 @@ config SERIAL_8250_NI
To compile this driver as a module, choose M here: the module
will be called 8250_ni.
+config SERIAL_8250_PRUSS
+ tristate "TI PRU-ICSS UART support"
+ depends on SERIAL_8250
+ depends on (PRU_REMOTEPROC && TI_PRUSS_INTC) || COMPILE_TEST
+ help
+ This driver is to support the UART module in PRU-ICSS which is
+ available in some TI platforms.
+
+ To compile this driver as a module, chose M here: the
+ module will be called 8250_pruss.
+
config SERIAL_OF_PLATFORM
tristate "Devicetree based probing for 8250 ports"
depends on SERIAL_8250 && OF
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index b04eeda03b23..3132b4f40a34 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_SERIAL_8250_PARISC) += 8250_parisc.o
obj-$(CONFIG_SERIAL_8250_PCI) += 8250_pci.o
obj-$(CONFIG_SERIAL_8250_PCI1XXXX) += 8250_pci1xxxx.o
obj-$(CONFIG_SERIAL_8250_PERICOM) += 8250_pericom.o
+obj-$(CONFIG_SERIAL_8250_PRUSS) += 8250_pruss.o
obj-$(CONFIG_SERIAL_8250_PXA) += 8250_pxa.o
obj-$(CONFIG_SERIAL_8250_RT288X) += 8250_rt288x.o
obj-$(CONFIG_SERIAL_8250_CS) += serial_cs.o
--
2.49.0
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