[PATCH] powerpc: serial port discovery (#2)

This moves the discovery of legacy serial ports to a separate file,
makes it common to ppc32 and ppc64, and reworks it to use the new OF
address translators to get to the ports early. This new version can also
detect some PCI serial cards using legacy chips and will probably match
those discovered port with the default console choice.

Only ppc64 gets udbg still yet, unifying udbg isn't finished yet.

It also adds some speed-probing code to udbg so that the default console
can come up at the same speed it was set to by the firmware.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 478 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/legacy_serial.c b/arch/powerpc/kernel/legacy_serial.c
new file mode 100644
index 000000000000..28ad50e424a9
--- /dev/null
+++ b/arch/powerpc/kernel/legacy_serial.c
@@ -0,0 +1,478 @@
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/serial.h>
+#include <linux/serial_8250.h>
+#include <linux/serial_core.h>
+#include <linux/console.h>
+#include <linux/pci.h>
+#include <asm/io.h>
+#include <asm/mmu.h>
+#include <asm/prom.h>
+#include <asm/serial.h>
+#include <asm/udbg.h>
+#include <asm/pci-bridge.h>
+#include <asm/ppc-pci.h>
+
+#undef DEBUG
+
+#ifdef DEBUG
+#define DBG(fmt...) do { printk(fmt); } while(0)
+#else
+#define DBG(fmt...) do { } while(0)
+#endif
+
+#define MAX_LEGACY_SERIAL_PORTS	8
+
+static struct plat_serial8250_port
+legacy_serial_ports[MAX_LEGACY_SERIAL_PORTS+1];
+static struct legacy_serial_info {
+	struct device_node		*np;
+	unsigned int			speed;
+	unsigned int			clock;
+	phys_addr_t			taddr;
+} legacy_serial_infos[MAX_LEGACY_SERIAL_PORTS];
+static unsigned int legacy_serial_count;
+static int legacy_serial_console = -1;
+
+static int __init add_legacy_port(struct device_node *np, int want_index,
+				  int iotype, phys_addr_t base,
+				  phys_addr_t taddr, unsigned long irq)
+{
+	u32 *clk, *spd, clock;
+	int index;
+
+	/* get clock freq. if present */
+	clk = (u32 *)get_property(np, "clock-frequency", NULL);
+	clock = clk ? *clk : BASE_BAUD * 16;
+
+	/* get default speed if present */
+	spd = (u32 *)get_property(np, "current-speed", NULL);
+
+	/* If we have a location index, then try to use it */
+	if (want_index >= 0 && want_index < MAX_LEGACY_SERIAL_PORTS)
+		index = want_index;
+	else
+		index = legacy_serial_count;
+
+	/* if our index is still out of range, that mean that
+	 * array is full, we could scan for a free slot but that
+	 * make little sense to bother, just skip the port
+	 */
+	if (index >= MAX_LEGACY_SERIAL_PORTS)
+		return -1;
+	if (index >= legacy_serial_count)
+		legacy_serial_count = index + 1;
+
+	/* Check if there is a port who already claimed our slot */
+	if (legacy_serial_infos[index].np != 0) {
+		/* if we still have some room, move it, else override */
+		if (legacy_serial_count < MAX_LEGACY_SERIAL_PORTS) {
+			printk(KERN_INFO "Moved legacy port %d -> %d\n",
+			       index, legacy_serial_count);
+			legacy_serial_ports[legacy_serial_count] =
+				legacy_serial_ports[index];
+			legacy_serial_infos[legacy_serial_count] =
+				legacy_serial_infos[index];
+			legacy_serial_count++;
+		} else {
+			printk(KERN_INFO "Replacing legacy port %d\n", index);
+		}
+	}
+
+	/* Now fill the entry */
+	memset(&legacy_serial_ports[index], 0,
+	       sizeof(struct plat_serial8250_port));
+	if (iotype == UPIO_PORT)
+		legacy_serial_ports[index].iobase = base;
+	else
+		legacy_serial_ports[index].membase = (void __iomem *)base;
+	legacy_serial_ports[index].iotype = iotype;
+	legacy_serial_ports[index].uartclk = clock;
+	legacy_serial_ports[index].irq = irq;
+	legacy_serial_ports[index].flags = ASYNC_BOOT_AUTOCONF;
+	legacy_serial_infos[index].taddr = taddr;
+	legacy_serial_infos[index].np = of_node_get(np);
+	legacy_serial_infos[index].clock = clock;
+	legacy_serial_infos[index].speed = spd ? *spd : 0;
+
+	printk(KERN_INFO "Found legacy serial port %d for %s\n",
+	       index, np->full_name);
+	printk(KERN_INFO "  %s=%llx, taddr=%llx, irq=%lx, clk=%d, speed=%d\n",
+	       (iotype == UPIO_PORT) ? "port" : "mem",
+	       (unsigned long long)base, (unsigned long long)taddr, irq,
+	       legacy_serial_ports[index].uartclk,
+	       legacy_serial_infos[index].speed);
+
+	return index;
+}
+
+static int __init add_legacy_isa_port(struct device_node *np,
+				      struct device_node *isa_bridge)
+{
+	u32 *reg;
+	char *typep;
+	int index = -1;
+	phys_addr_t taddr;
+
+	/* Get the ISA port number */
+	reg = (u32 *)get_property(np, "reg", NULL);
+	if (reg == NULL)
+		return -1;
+
+	/* Verify it's an IO port, we don't support anything else */
+	if (!(reg[0] & 0x00000001))
+		return -1;
+
+	/* Now look for an "ibm,aix-loc" property that gives us ordering
+	 * if any...
+	 */
+	typep = (char *)get_property(np, "ibm,aix-loc", NULL);
+
+	/* If we have a location index, then use it */
+	if (typep && *typep == 'S')
+		index = simple_strtol(typep+1, NULL, 0) - 1;
+
+	/* Translate ISA address */
+	taddr = of_translate_address(np, reg);
+
+	/* Add port, irq will be dealt with later */
+	return add_legacy_port(np, index, UPIO_PORT, reg[1], taddr, NO_IRQ);
+
+}
+
+static int __init add_legacy_pci_port(struct device_node *np,
+				      struct device_node *pci_dev)
+{
+	phys_addr_t addr, base;
+	u32 *addrp;
+	int iotype, index = -1;
+
+#if 0
+	/* We only support ports that have a clock frequency properly
+	 * encoded in the device-tree (that is have an fcode). Anything
+	 * else can't be used that early and will be normally probed by
+	 * the generic 8250_pci driver later on.
+	 */
+	if (get_property(np, "clock-frequency", NULL) == NULL)
+		return -1;
+#endif
+
+	/* Get the PCI address. Assume BAR 0 */
+	addrp = of_get_pci_address(pci_dev, 0, NULL);
+	if (addrp == NULL)
+		return -1;
+
+	/* We only support BAR 0 for now */
+	iotype = (addrp[0] & 0x02000000) ? UPIO_MEM : UPIO_PORT;
+	addr = of_translate_address(pci_dev, addrp);
+
+	/* Set the IO base to the same as the translated address for MMIO,
+	 * or to the domain local IO base for PIO (it will be fixed up later)
+	 */
+	if (iotype == UPIO_MEM)
+		base = addr;
+	else
+		base = addrp[2];
+
+	/* Try to guess an index... If we have subdevices of the pci dev,
+	 * we get to their "reg" property
+	 */
+	if (np != pci_dev) {
+		u32 *reg = (u32 *)get_property(np, "reg", NULL);
+		if (reg && (*reg < 4))
+			index = legacy_serial_count + *reg;
+	}
+
+	/* Add port, irq will be dealt with later. We passed a translated
+	 * IO port value. It will be fixed up later along with the irq
+	 */
+	return add_legacy_port(np, index, iotype, base, addr, NO_IRQ);
+}
+
+/*
+ * This is called very early, as part of setup_system() or eventually
+ * setup_arch(), basically before anything else in this file. This function
+ * will try to build a list of all the available 8250-compatible serial ports
+ * in the machine using the Open Firmware device-tree. It currently only deals
+ * with ISA and PCI busses but could be extended. It allows a very early boot
+ * console to be initialized, that list is also used later to provide 8250 with
+ * the machine non-PCI ports and to properly pick the default console port
+ */
+void __init find_legacy_serial_ports(void)
+{
+	struct device_node *np, *stdout;
+	char *path;
+	int index;
+
+	DBG(" -> find_legacy_serial_port()\n");
+
+	/* Now find out if one of these is out firmware console */
+	path = (char *)get_property(of_chosen, "linux,stdout-path", NULL);
+	if (path == NULL) {
+		DBG(" no linux,stdout-path !\n");
+		return;
+	}
+	stdout = of_find_node_by_path(path);
+	if (stdout) {
+		DBG("stdout is %s\n", stdout->full_name);
+	}
+
+	/* First fill our array with ISA ports */
+	for (np = NULL; (np = of_find_node_by_type(np, "serial"));) {
+		struct device_node *isa = of_get_parent(np);
+		if (isa && !strcmp(isa->name, "isa")) {
+			index = add_legacy_isa_port(np, isa);
+			if (index >= 0 && np == stdout)
+				legacy_serial_console = index;
+		}
+		of_node_put(isa);
+	}
+
+	/* Next, try to locate PCI ports */
+	for (np = NULL; (np = of_find_all_nodes(np));) {
+		struct device_node *pci, *parent = of_get_parent(np);
+		if (parent && !strcmp(parent->name, "isa")) {
+			of_node_put(parent);
+			continue;
+		}
+		if (strcmp(np->name, "serial") && strcmp(np->type, "serial")) {
+			of_node_put(parent);
+			continue;
+		}
+		/* Check for known pciclass, and also check wether we have
+		 * a device with child nodes for ports or not
+		 */
+		if (device_is_compatible(np, "pciclass,0700") ||
+		    device_is_compatible(np, "pciclass,070002"))
+			pci = np;
+		else if (device_is_compatible(parent, "pciclass,0700") ||
+			 device_is_compatible(parent, "pciclass,070002"))
+			pci = parent;
+		else {
+			of_node_put(parent);
+			continue;
+		}
+		index = add_legacy_pci_port(np, pci);
+		if (index >= 0 && np == stdout)
+			legacy_serial_console = index;
+		of_node_put(parent);
+	}
+
+	DBG("legacy_serial_console = %d\n", legacy_serial_console);
+
+	/* udbg is 64 bits only for now, that will change soon though ... */
+#ifdef CONFIG_PPC64
+	while (legacy_serial_console >= 0) {
+		struct legacy_serial_info *info =
+			&legacy_serial_infos[legacy_serial_console];
+		void __iomem *addr;
+
+		if (info->taddr == 0)
+			break;
+		addr = ioremap(info->taddr, 0x1000);
+		if (addr == NULL)
+			break;
+		if (info->speed == 0)
+			info->speed = udbg_probe_uart_speed(addr, info->clock);
+		DBG("default console speed = %d\n", info->speed);
+		udbg_init_uart(addr, info->speed, info->clock);
+		break;
+	}
+#endif /* CONFIG_PPC64 */
+
+	DBG(" <- find_legacy_serial_port()\n");
+}
+
+static struct platform_device serial_device = {
+	.name	= "serial8250",
+	.id	= PLAT8250_DEV_PLATFORM,
+	.dev	= {
+		.platform_data = legacy_serial_ports,
+	},
+};
+
+static void __init fixup_port_irq(int index,
+				  struct device_node *np,
+				  struct plat_serial8250_port *port)
+{
+	DBG("fixup_port_irq(%d)\n", index);
+
+	/* Check for interrupts in that node */
+	if (np->n_intrs > 0) {
+		port->irq = np->intrs[0].line;
+		DBG(" port %d (%s), irq=%d\n",
+		    index, np->full_name, port->irq);
+		return;
+	}
+
+	/* Check for interrupts in the parent */
+	np = of_get_parent(np);
+	if (np == NULL)
+		return;
+
+	if (np->n_intrs > 0) {
+		port->irq = np->intrs[0].line;
+		DBG(" port %d (%s), irq=%d\n",
+		    index, np->full_name, port->irq);
+	}
+	of_node_put(np);
+}
+
+static void __init fixup_port_pio(int index,
+				  struct device_node *np,
+				  struct plat_serial8250_port *port)
+{
+	struct pci_controller *hose;
+
+	DBG("fixup_port_pio(%d)\n", index);
+
+	hose = pci_find_hose_for_OF_device(np);
+	if (hose) {
+		unsigned long offset = (unsigned long)hose->io_base_virt -
+#ifdef CONFIG_PPC64
+			pci_io_base;
+#else
+			isa_io_base;
+#endif
+		DBG("port %d, IO %lx -> %lx\n",
+		    index, port->iobase, port->iobase + offset);
+		port->iobase += offset;
+	}
+}
+
+/*
+ * This is called as an arch initcall, hopefully before the PCI bus is
+ * probed and/or the 8250 driver loaded since we need to register our
+ * platform devices before 8250 PCI ones are detected as some of them
+ * must properly "override" the platform ones.
+ *
+ * This function fixes up the interrupt value for platform ports as it
+ * couldn't be done earlier before interrupt maps have been parsed. It
+ * also "corrects" the IO address for PIO ports for the same reason,
+ * since earlier, the PHBs virtual IO space wasn't assigned yet. It then
+ * registers all those platform ports for use by the 8250 driver when it
+ * finally loads.
+ */
+static int __init serial_dev_init(void)
+{
+	int i;
+
+	if (legacy_serial_count == 0)
+		return -ENODEV;
+
+	/*
+	 * Before we register the platfrom serial devices, we need
+	 * to fixup their interrutps and their IO ports.
+	 */
+	DBG("Fixing serial ports interrupts and IO ports ...\n");
+
+	for (i = 0; i < legacy_serial_count; i++) {
+		struct plat_serial8250_port *port = &legacy_serial_ports[i];
+		struct device_node *np = legacy_serial_infos[i].np;
+
+		if (port->irq == NO_IRQ)
+			fixup_port_irq(i, np, port);
+		if (port->iotype == UPIO_PORT)
+			fixup_port_pio(i, np, port);
+	}
+
+	DBG("Registering platform serial ports\n");
+
+	return platform_device_register(&serial_device);
+}
+arch_initcall(serial_dev_init);
+
+
+/*
+ * This is called very early, as part of console_init() (typically just after
+ * time_init()). This function is respondible for trying to find a good
+ * default console on serial ports. It tries to match the open firmware
+ * default output with one of the available serial console drivers, either
+ * one of the platform serial ports that have been probed earlier by
+ * find_legacy_serial_ports() or some more platform specific ones.
+ */
+static int __init check_legacy_serial_console(void)
+{
+	struct device_node *prom_stdout = NULL;
+	int speed = 0, offset = 0;
+	char *name;
+	u32 *spd;
+
+	DBG(" -> check_legacy_serial_console()\n");
+
+	/* The user has requested a console so this is already set up. */
+	if (strstr(saved_command_line, "console=")) {
+		DBG(" console was specified !\n");
+		return -EBUSY;
+	}
+
+	if (!of_chosen) {
+		DBG(" of_chosen is NULL !\n");
+		return -ENODEV;
+	}
+	/* We are getting a weird phandle from OF ... */
+	/* ... So use the full path instead */
+	name = (char *)get_property(of_chosen, "linux,stdout-path", NULL);
+	if (name == NULL) {
+		DBG(" no linux,stdout-path !\n");
+		return -ENODEV;
+	}
+	prom_stdout = of_find_node_by_path(name);
+	if (!prom_stdout) {
+		DBG(" can't find stdout package %s !\n", name);
+		return -ENODEV;
+	}
+	DBG("stdout is %s\n", prom_stdout->full_name);
+
+	name = (char *)get_property(prom_stdout, "name", NULL);
+	if (!name) {
+		DBG(" stdout package has no name !\n");
+		goto not_found;
+	}
+	spd = (u32 *)get_property(prom_stdout, "current-speed", NULL);
+	if (spd)
+		speed = *spd;
+
+	if (0)
+		;
+#ifdef CONFIG_SERIAL_8250_CONSOLE
+	else if (strcmp(name, "serial") == 0) {
+		int i;
+		/* Look for it in probed array */
+		for (i = 0; i < legacy_serial_count; i++) {
+			if (prom_stdout != legacy_serial_infos[i].np)
+				continue;
+			offset = i;
+			speed = legacy_serial_infos[i].speed;
+			break;
+		}
+		if (i >= legacy_serial_count)
+			goto not_found;
+	}
+#endif /* CONFIG_SERIAL_8250_CONSOLE */
+#ifdef CONFIG_SERIAL_PMACZILOG_CONSOLE
+	else if (strcmp(name, "ch-a") == 0)
+		offset = 0;
+	else if (strcmp(name, "ch-b") == 0)
+		offset = 1;
+#endif /* CONFIG_SERIAL_PMACZILOG_CONSOLE */
+	else
+		goto not_found;
+	of_node_put(prom_stdout);
+
+	DBG("Found serial console at ttyS%d\n", offset);
+
+	if (speed) {
+		static char __initdata opt[16];
+		sprintf(opt, "%d", speed);
+		return add_preferred_console("ttyS", offset, opt);
+	} else
+		return add_preferred_console("ttyS", offset, NULL);
+
+ not_found:
+	DBG("No preferred console found !\n");
+	of_node_put(prom_stdout);
+	return -ENODEV;
+}
+console_initcall(check_legacy_serial_console);
+