On Tue, Mar 28, 2017 at 8:44 AM, Joel Stanley <joel@xxxxxxxxx> wrote: > This change adds a driver for the 16550-based Aspeed virtual UART > device. We use a similar process to the of_serial driver for device > probe, but expose some VUART-specific functions through sysfs too. > > OpenPOWER host firmware doesn't like it when the host-side of the > VUART's FIFO is not drained. This driver only disables host TX discard > mode when the port is in use. We set the VUART enabled bit when we bind > to the device, and clear it on unbind. > > We don't want to do this on open/release, as the host may be using this > bit to configure serial output modes, which is independent of whether > the devices has been opened by BMC userspace. > Documentation/devicetree/bindings/serial/8250.txt | 2 + > drivers/tty/serial/Kconfig | 10 + > drivers/tty/serial/Makefile | 1 + > drivers/tty/serial/aspeed-vuart.c | 335 ++++++++++++++++++++++ And why it's not under 8250 folder? > +#include <linux/device.h> > +#include <linux/module.h> > +#include <linux/of_address.h> > +#include <linux/of_irq.h> > +#include <linux/of_platform.h> > +#include <linux/clk.h> > + > +#include "8250/8250.h" > + > +#define AST_VUART_GCRA 0x20 > +#define AST_VUART_GCRA_VUART_EN 0x01 > +#define AST_VUART_GCRA_HOST_TX_DISCARD 0x20 BIT(x) ? > +#define AST_VUART_GCRB 0x24 > +#define AST_VUART_GCRB_HOST_SIRQ_MASK 0xf0 GENMASK() ? > +#define AST_VUART_GCRB_HOST_SIRQ_SHIFT 4 > +#define AST_VUART_ADDRL 0x28 > +#define AST_VUART_ADDRH 0x2c > + > +struct ast_vuart { > + struct platform_device *pdev; Ususally there is no need to keep pointer to sturct platform_device, rahter we need struct device *dev. > + void __iomem *regs; > + struct clk *clk; > + int line; > +}; > + > +static ssize_t ast_vuart_show_addr(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct ast_vuart *vuart = dev_get_drvdata(dev); > + u16 addr; > + > + addr = (readb(vuart->regs + AST_VUART_ADDRH) << 8) | > + (readb(vuart->regs + AST_VUART_ADDRL)); It looks like you have register shift 2 bits and byte accessors. We have some helpers for that (serial_in() / serial_out() or alike). > + > + return snprintf(buf, PAGE_SIZE - 1, "0x%x\n", addr); > +} > + > +static ssize_t ast_vuart_set_addr(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + struct ast_vuart *vuart = dev_get_drvdata(dev); > + unsigned long val; > + int err; > + > + err = kstrtoul(buf, 0, &val); > + if (err) > + return err; > + > + writeb((val >> 8) & 0xff, vuart->regs + AST_VUART_ADDRH); > + writeb((val >> 0) & 0xff, vuart->regs + AST_VUART_ADDRL); Useless & 0xff. > + > + return count; > +} > +} > + > + Extra empty line. > +/** If you are going to use kernel doc do it in accordance with howto. > + * The device tree parsing code here is heavily based on that of the of_serial > + * driver, but we have a few core differences, as we need to use our own > + * ioremapping for extra register support > + */ > +static int ast_vuart_probe(struct platform_device *pdev) > +{ > + struct uart_8250_port port; > + struct resource resource; > + struct ast_vuart *vuart; > + struct device_node *np; > + u32 clk, prop; > + int rc; > + > + np = pdev->dev.of_node; And if np == NULL? > + > + vuart = devm_kzalloc(&pdev->dev, sizeof(*vuart), GFP_KERNEL); > + if (!vuart) > + return -ENOMEM; > + > + vuart->pdev = pdev; > + rc = of_address_to_resource(np, 0, &resource); > + if (rc) { > + dev_warn(&pdev->dev, "invalid address\n"); > + return rc; > + } > + > + /* create our own mapping for VUART-specific registers */ > + vuart->regs = devm_ioremap_resource(&pdev->dev, &resource); > + if (IS_ERR(vuart->regs)) { > + dev_warn(&pdev->dev, "failed to map registers\n"); > + return PTR_ERR(vuart->regs); > + } Can you use platform_get-resource() + devm_ioremap_resource() ? If no, why? > + > + memset(&port, 0, sizeof(port)); > + port.port.private_data = vuart; > + port.port.membase = vuart->regs; > + port.port.mapbase = resource.start; > + port.port.mapsize = resource_size(&resource); > + port.port.startup = ast_vuart_startup; > + port.port.shutdown = ast_vuart_shutdown; > + > + if (of_property_read_u32(np, "clock-frequency", &clk)) { > + vuart->clk = devm_clk_get(&pdev->dev, NULL); > + if (IS_ERR(vuart->clk)) { > + dev_warn(&pdev->dev, > + "clk or clock-frequency not defined\n"); > + return PTR_ERR(vuart->clk); > + } > + > + rc = clk_prepare_enable(vuart->clk); > + if (rc < 0) > + return rc; > + > + clk = clk_get_rate(vuart->clk); > + } > + > + /* If current-speed was set, then try not to change it. */ > + if (of_property_read_u32(np, "current-speed", &prop) == 0) > + port.port.custom_divisor = clk / (16 * prop); > + > + /* Check for shifted address mapping */ > + if (of_property_read_u32(np, "reg-offset", &prop) == 0) > + port.port.mapbase += prop; > + > + /* Check for registers offset within the devices address range */ > + if (of_property_read_u32(np, "reg-shift", &prop) == 0) > + port.port.regshift = prop; > + > + /* Check for fifo size */ > + if (of_property_read_u32(np, "fifo-size", &prop) == 0) > + port.port.fifosize = prop; Perhaps you need other way around, check for error and supply a default in such case. > + > + /* Check for a fixed line number */ > + rc = of_alias_get_id(np, "serial"); > + if (rc >= 0) > + port.port.line = rc; > + > + port.port.irq = irq_of_parse_and_map(np, 0); > + port.port.irqflags = IRQF_SHARED; This is set by core. You already supplied correct flag for that below. > + port.port.iotype = UPIO_MEM; > + if (of_property_read_u32(np, "reg-io-width", &prop) == 0) { You hide an error code from of_property_read_u32() here. Why? And if there is an error you are continuing with what? 0? > + switch (prop) { > + case 1: > + port.port.iotype = UPIO_MEM; > + break; > + case 4: > + port.port.iotype = of_device_is_big_endian(np) ? > + UPIO_MEM32BE : UPIO_MEM32; > + break; > + default: > + dev_warn(&pdev->dev, "unsupported reg-io-width (%d)\n", > + prop); > + rc = -EINVAL; > + goto err_clk_disable; > + } > + } > + > + port.port.type = PORT_16550A; > + port.port.uartclk = clk; > + port.port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF > + | UPF_FIXED_PORT | UPF_FIXED_TYPE | UPF_NO_THRE_TEST; > + > + if (of_find_property(np, "no-loopback-test", NULL)) > + port.port.flags |= UPF_SKIP_TEST; You perhaps meant _read_bool() for sake of consistency. > + > + port.port.dev = &pdev->dev; > + > + if (port.port.fifosize) > + port.capabilities = UART_CAP_FIFO; > + > + if (of_property_read_bool(pdev->dev.of_node, > + "auto-flow-control")) One line? > + port.capabilities |= UART_CAP_AFE; > + > + rc = serial8250_register_8250_port(&port); > + if (rc < 0) > + goto err_clk_disable; > + > + > + vuart->line = rc; > + ast_vuart_set_enabled(vuart, true); > + ast_vuart_set_host_tx_discard(vuart, true); > + platform_set_drvdata(pdev, vuart); > + > + /* extra sysfs control */ > + rc = device_create_file(&pdev->dev, &dev_attr_lpc_address); > + if (rc) > + dev_warn(&pdev->dev, "can't create lpc_address file\n"); > + rc = device_create_file(&pdev->dev, &dev_attr_sirq); > + if (rc) > + dev_warn(&pdev->dev, "can't create sirq file\n"); > + > + return 0; > + > +err_clk_disable: > + if (vuart->clk) > + clk_disable_unprepare(vuart->clk); > + > + irq_dispose_mapping(port.port.irq); > + return rc; > +} > + > +static int ast_vuart_remove(struct platform_device *pdev) > +{ > + struct ast_vuart *vuart = platform_get_drvdata(pdev); > + > + ast_vuart_set_enabled(vuart, false); > + > + if (vuart->clk) > + clk_disable_unprepare(vuart->clk); > + return 0; > +} -- With Best Regards, Andy Shevchenk -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html