Hi Bin,
Please don't drop lists (or other addressees) from patch revisions.
[ +cc linux-serial]
On 05/22/2015 12:06 PM, Bin Gao wrote:
> On some Intel Atom SoCs, the legacy IO port UART(0x3F8) is not available.
> Instead, a 8250 compatible PCI uart can be used as early console.
> This patch adds pci support to the 8250 early console driver uart8250.
> For example, to enable pci uart(00:21.3) as early console on these
> platforms, append the following line to the kernel command line
> (assume baud rate is 115200):
> earlyprintk=uart8250,pci32,0:24.2,115200n8
>
> Signed-off-by: Bin Gao <bin....@intel.com>
> ---
> Changes in v4:
> - moved PCI_EARLY definition from arch/x86/Kconfig to drivers/pci/Kconfig
> - added 'earlyprintk' for x86 as alias to the early param 'earlycon'
> arch/x86/Kconfig | 1 +
> drivers/pci/Kconfig | 11 +++
> drivers/tty/serial/earlycon.c | 9 +++
> drivers/tty/serial/serial_core.c | 145
> ++++++++++++++++++++++++++++++++++++++-
Please update Documentation/kernel-parameters.txt with pci-specific
earlycon parameter formats.
> 4 files changed, 164 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 226d569..bdedd61 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -143,6 +143,7 @@ config X86
> select ACPI_LEGACY_TABLES_LOOKUP if ACPI
> select X86_FEATURE_NAMES if PROC_FS
> select SRCU
> + select PCI_EARLY if PCI
>
> config INSTRUCTION_DECODER
> def_bool y
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index 7a8f1c5..4f0f055 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -114,4 +114,15 @@ config PCI_LABEL
> def_bool y if (DMI || ACPI)
> select NLS
>
> +config PCI_EARLY
> + bool "Early PCI access"
> + depends on PCI
> + default n
> + help
> + This option indicates that a group of APIs are available (in
> + asm/pci-direct.h) so the kernel can access pci config registers
> + before the PCI subsystem is initialized. Any arch that supports
> + early pci APIs should enable this option which is required by
> + arch independent codes, e.g. uart8250 pci early console driver.
> +
> source "drivers/pci/host/Kconfig"
> diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
> index 6dc471e..63ae60e 100644
> --- a/drivers/tty/serial/earlycon.c
> +++ b/drivers/tty/serial/earlycon.c
> @@ -193,6 +193,15 @@ static int __init param_setup_earlycon(char *buf)
> }
> early_param("earlycon", param_setup_earlycon);
>
> +/* x86 uses "earlyprintk=xxx", so we keep the compatibility here */
> +#ifdef CONFIG_X86
> +static int __init param_setup_earlycon_x86(char *buf)
> +{
> + return param_setup_earlycon(buf);
> +}
> +early_param("earlyprintk", param_setup_earlycon_x86);
> +#endif
> +
Please move this hunk to patch 2/2.
FYI, there is a proposal to evaluate "earlyprintk=" earlier than
parse_early_params(), which this would break.
https://lkml.org/lkml/2015/5/18/127
> int __init of_setup_earlycon(unsigned long addr,
> int (*setup)(struct earlycon_device *, const char
> *))
> {
> diff --git a/drivers/tty/serial/serial_core.c
> b/drivers/tty/serial/serial_core.c
> index 0b7bb12..19ca2a0 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -34,10 +34,15 @@
> #include <linux/serial_core.h>
> #include <linux/delay.h>
> #include <linux/mutex.h>
> +#include <linux/pci_regs.h>
>
> #include <asm/irq.h>
> #include <asm/uaccess.h>
>
> +#ifdef CONFIG_PCI_EARLY
> +#include <asm/pci-direct.h>
> +#endif
> +
> /*
> * This is used to lock changes in serial line configuration.
> */
> @@ -1808,6 +1813,110 @@ uart_get_console(struct uart_port *ports, int nr,
> struct console *co)
> return ports + idx;
> }
>
> +static int parse_bdf(char *options, char **endp, char delimiter, u8 *val)
If this function is only used from parse_pci_options(), please enclose it
in #ifdef CONFIG_PCI_EARLY scope with parse_pci_options().
> +{
> + char str[4]; /* max 3 chars, plus a NULL terminator */
> + char *p = options;
> + int i = 0;
> +
> + while (*p) {
> + if (i >= 4)
> + return -EINVAL;
> +
> + if (*p == delimiter) {
> + str[i++] = 0;
> + if (endp)
> + *endp = p + 1;
> + return kstrtou8(str, 10, val); /* decimal, no hex */
> + }
> +
> + str[i++] = *p++;
> + }
Is all this to avoid using simple_strtoul()?
If yes, I'd rather you use simple_strtoul() like the rest of the console
code and ignore the (misguided) advice that simple_strtoul() is obsolete.
The code above is exactly what is wrong with the kstrto* api.
> +
> + return -EINVAL;
> +}
> +
> +#ifdef CONFIG_PCI_EARLY
> +/*
> + * The whole pci option from the command line is: pci[32],B:D.F[,options]
> + * Examples:
> + * pci,0:21.3,115200n8
> + * pci32,0:21.3
> + * Here pci32 means 8250 UART registers are 32-bit width(regshift = 2).
> + * pci means 8250 UART registers are 8-bit width(regshift = 0).
> + * B,D and F are bus, device and function, in decimal(not hex).
> + * The additional options(115200n8) would be parsed by the earlycon
> framework.
> + *
> + * @options: the pci options
> + * @phys: the pointer to return pci mem or io address
> + * return: <0: error
> + * 0: pci mem
> + * 1: pci io
> + */
> +static int parse_pci_options(char *options, unsigned long *phys)
> +{
> + u8 bus, dev, func;
> + char *endp;
> + u64 bar0;
> + u16 cmd;
> + int pci_io = 0;
> +
> + if (!early_pci_allowed()) {
> + pr_err("earlycon pci not available(early pci not allowed)\n");
Error message is redundant.
> + return -EINVAL;
> + }
> +
> + /* We come here with options=B:D.F[,options] */
> + if (parse_bdf(options, &endp, ':', &bus))
> + goto failed;
> +
> + if (parse_bdf(endp, &endp, '.', &dev))
> + goto failed;
> +
> + if (parse_bdf(endp, &endp, ',', &func))
> + goto failed;
> +
> + /*
> + * On these platforms class code in pci config is broken,
^^^^^^^^^^^^^^^
which platforms?
> + * so skip checking it.
> + */
> +
> + bar0 = read_pci_config(bus, dev, func, PCI_BASE_ADDRESS_0);
> +
> + /* The BAR is IO or Memory? */
> + if ((bar0 & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO)
> + pci_io = 1;
> +
> + if ((bar0 & PCI_BASE_ADDRESS_MEM_TYPE_MASK) ==
> + PCI_BASE_ADDRESS_MEM_TYPE_64)
> + bar0 |= (u64)read_pci_config(bus, dev, func,
> + PCI_BASE_ADDRESS_0 + 4) << 32;
> +
> + *phys = bar0 & (pci_io ? PCI_BASE_ADDRESS_IO_MASK :
> + PCI_BASE_ADDRESS_MEM_MASK);
> +
> + /* Enable address decoding */
> + cmd = read_pci_config_16(bus, dev, func, PCI_COMMAND);
> + write_pci_config_16(bus, dev, func, PCI_COMMAND,
> + cmd | (pci_io ? PCI_COMMAND_IO : PCI_COMMAND_MEMORY));
> +
> + pr_info("Use 8250 uart at PCI 0000:%02u:%02u.%01u as early console\n",
> + bus, dev, func);
I think one earlycon banner is sufficient; you could make this pr_debug()
instead. Existing convention for earlycon messages is
"earlycon: ...."
> + return pci_io;
> +
> +failed:
> + pr_err("Invalid earlycon pci parameters\n");
> + return -EINVAL;
> +}
> +
> +#else
> +static int parse_pci_options(char *options, unsigned long *phys)
> +{
> + pr_err("earlycon pci not available(need CONFIG_PCI_EARLY)\n");
"earlycon: PCI not supported (requires CONFIG_PCI_EARLY=y)" ?
> + return -EINVAL;
> +}
> +#endif
> +
> /**
> * uart_parse_earlycon - Parse earlycon options
> * @p: ptr to 2nd field (ie., just beyond '<name>,')
> @@ -1816,8 +1925,9 @@ uart_get_console(struct uart_port *ports, int nr,
> struct console *co)
> * @options: ptr for <options> field; NULL if not present (out)
> *
> * Decodes earlycon kernel command line parameters of the form
> - * earlycon=<name>,io|mmio|mmio32,<addr>,<options>
> + * earlycon=<name>,io|mmio|mmio32|pci|pci32,<addr>,<options>
Document the pci/pci32 format separately because
earlycon=uart8250,pci32,<addr>,<options> is not a valid form.
> * console=<name>,io|mmio|mmio32,<addr>,<options>
> + * For pci/pci32, the <addr> format is B:D.F, e.g. 0:24.2
> *
> * The optional form
> * earlycon=<name>,0x<addr>,<options>
> @@ -1829,12 +1939,23 @@ uart_get_console(struct uart_port *ports, int nr,
> struct console *co)
> int uart_parse_earlycon(char *p, unsigned char *iotype, unsigned long *addr,
> char **options)
> {
> + int pci = 0, ret;
> + unsigned long phys;
> +
> if (strncmp(p, "mmio,", 5) == 0) {
> *iotype = UPIO_MEM;
> p += 5;
> } else if (strncmp(p, "mmio32,", 7) == 0) {
> *iotype = UPIO_MEM32;
> p += 7;
> + } else if (strncmp(p, "pci,", 4) == 0) {
> + pci = 1;
> + p += 4;
> + ret = parse_pci_options(p, &phys);
> + } else if (strncmp(p, "pci32,", 6) == 0) {
> + pci = 2;
> + p += 6;
> + ret = parse_pci_options(p, &phys);
> } else if (strncmp(p, "io,", 3) == 0) {
> *iotype = UPIO_PORT;
> p += 3;
> @@ -1844,7 +1965,27 @@ int uart_parse_earlycon(char *p, unsigned char
> *iotype, unsigned long *addr,
> return -EINVAL;
> }
>
> - *addr = simple_strtoul(p, NULL, 0);
> + if (pci) {
> + if (ret < 0) /* error */
> + return ret;
> +
> + /*
> + * Once PCI mem/io is read from PCI BAR, we can reuse
> + * mmio/mmio32/io type to minimize code change.
> + */
> + if (ret > 0) /* PCI io */
> + *iotype = UPIO_PORT;
> + else { /* ret = 0: PCI mem */
> + if (pci == 2)
> + *iotype = UPIO_MEM32;
> + else
> + *iotype = UPIO_MEM;
> + }
> +
> + *addr = phys;
> + } else
> + *addr = simple_strtoul(p, NULL, 0);
> +
I'd like to see this refactored without the logic steering locals.
Like this:
if (strncmp(p, "mmio,", 5) == 0) {
*iotype = UPIO_MEM;
p += 5;
+ *addr = simple_strtoul(p, NULL, 0);
} else if (strncmp(p, "mmio32,", 7) == 0) {
*iotype = UPIO_MEM32;
p += 7;
+ *addr = simple_strtoul(p, NULL, 0);
+ } else if (strncmp(p, "pci,", 4) == 0) {
+ pci = 1;
+ p += 4;
+ ret = parse_pci_options(p, addr);
+ if (ret < 0)
+ return ret;
+ *iotype = (ret > 0) ? UPIO_PORT : UPIO_MEM;
+ } else if (strncmp(p, "pci32,", 6) == 0) {
+ pci = 2;
+ p += 6;
+ ret = parse_pci_options(p, addr);
+ if (ret < 0)
+ return ret;
+ *iotype = (ret > 0) ? UPIO_PORT : UPIO_MEM32;
} else if (strncmp(p, "io,", 3) == 0) {
*iotype = UPIO_PORT;
p += 3;
+ *addr = simple_strtoul(p, NULL, 0);
Regards,
Peter Hurley
> - *addr = simple_strtoul(p, NULL, 0);
> p = strchr(p, ',');
> if (p)
> p++;
>
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