Re: [PATCH v3 10/15] thunderbolt: Add path setup code.

[Bjorn Helgaas <bhelgaas@google.com>]

On Mon, May 26, 2014 at 05:18:07PM +0200, Andreas Noever wrote:
> A thunderbolt path is a unidirectional channel between two thunderbolt
> ports. Two such paths are needed to establish a pci tunnel.
> 
> This patch introduces struct tb_path as well as a set of tb_path_*
> methods which are used do activate & deactive paths.

s/do activate & deactive/to activate & deactivate/

> Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
> ---
>  drivers/thunderbolt/Makefile |   2 +-
>  drivers/thunderbolt/path.c   | 215 +++++++++++++++++++++++++++++++++++++++++++
>  drivers/thunderbolt/switch.c |  34 +++++++
>  drivers/thunderbolt/tb.h     |  62 +++++++++++++
>  4 files changed, 312 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/thunderbolt/path.c
> 
> diff --git a/drivers/thunderbolt/Makefile b/drivers/thunderbolt/Makefile
> index 617b314..3532f36 100644
> --- a/drivers/thunderbolt/Makefile
> +++ b/drivers/thunderbolt/Makefile
> @@ -1,3 +1,3 @@
>  obj-${CONFIG_THUNDERBOLT} := thunderbolt.o
> -thunderbolt-objs := nhi.o ctl.o tb.o switch.o cap.o
> +thunderbolt-objs := nhi.o ctl.o tb.o switch.o cap.o path.o
>  
> diff --git a/drivers/thunderbolt/path.c b/drivers/thunderbolt/path.c
> new file mode 100644
> index 0000000..8fcf8a7
> --- /dev/null
> +++ b/drivers/thunderbolt/path.c
> @@ -0,0 +1,215 @@
> +/*
> + * Thunderbolt Cactus Ridge driver - path/tunnel functionality
> + *
> + * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/errno.h>
> +
> +#include "tb.h"
> +
> +
> +static void tb_dump_hop(struct tb_port *port, struct tb_regs_hop *hop)
> +{
> +	tb_port_info(port, " Hop through port %d to hop %d (%s)\n",
> +		     hop->out_port, hop->next_hop,
> +		     hop->enable ? "enabled" : "disabled");
> +	tb_port_info(port, "  Weight: %d Priority: %d Credits: %d Drop: %d\n",
> +		     hop->weight, hop->priority,
> +		     hop->initial_credits, hop->drop_packages);
> +	tb_port_info(port, "   Counter enabled: %d Counter index: %d\n",
> +		     hop->counter_enable, hop->counter);
> +	tb_port_info(port, "  Flow Control (In/Eg): %d/%d Shared Buffer (In/Eg): %d/%d\n",
> +		     hop->ingress_fc, hop->egress_fc,
> +		     hop->ingress_shared_buffer, hop->egress_shared_buffer);
> +	tb_port_info(port, "  Unknown1: %#x Unknown2: %#x Unknown3: %#x\n",
> +		     hop->unknown1, hop->unknown2, hop->unknown3);
> +}
> +
> +/**
> + * tb_path_alloc() - allocate a thunderbolt path
> + *
> + * Return: Returns a tb_path on success or NULL on failure.
> + */
> +struct tb_path *tb_path_alloc(struct tb *tb, int num_hops)
> +{
> +	struct tb_path *path = kzalloc(sizeof(*path), GFP_KERNEL);
> +	if (!path)
> +		return NULL;
> +	path->hops = kcalloc(num_hops, sizeof(*path->hops), GFP_KERNEL);
> +	if (!path->hops) {
> +		kfree(path);
> +		return NULL;
> +	}
> +	path->tb = tb;
> +	path->path_length = num_hops;
> +	return path;
> +}
> +
> +/**
> + * tb_path_free() - free a deactivated path
> + */
> +void tb_path_free(struct tb_path *path)
> +{
> +	if (path->activated) {
> +		tb_WARN(path->tb, "trying to free an activated path\n")
> +		return;
> +	}
> +	kfree(path->hops);
> +	kfree(path);
> +}
> +
> +static void __tb_path_deallocate_nfc(struct tb_path *path, int first_hop)
> +{
> +	int i, res;
> +	for (i = first_hop; i < path->path_length; i++) {
> +		res = tb_port_add_nfc_credits(path->hops[i].in_port,
> +					      -path->nfc_credits);
> +		if (res)
> +			tb_port_warn(path->hops[i].in_port,
> +				     "nfc credits deallocation failed for hop %d\n",
> +				     i);
> +	}
> +}
> +
> +static void __tb_path_deactivate_hops(struct tb_path *path, int first_hop)
> +{
> +	int i, res;
> +	struct tb_regs_hop hop = { };
> +	for (i = first_hop; i < path->path_length; i++) {
> +		res = tb_port_write(path->hops[i].in_port, &hop, TB_CFG_HOPS,
> +				    2 * path->hops[i].in_hop_index, 2);
> +		if (res)
> +			tb_port_warn(path->hops[i].in_port,
> +				     "hop deactivation failed for hop %d, index %d\n",
> +				     i, path->hops[i].in_hop_index);
> +	}
> +}
> +
> +void tb_path_deactivate(struct tb_path *path)
> +{
> +	if (!path->activated) {
> +		tb_WARN(path->tb, "trying to deactivate an inactive path\n");
> +		return;
> +	}
> +	tb_info(path->tb,
> +		"deactivating path from %llx:%x to %llx:%x\n",
> +		tb_route(path->hops[0].in_port->sw),
> +		path->hops[0].in_port->port,
> +		tb_route(path->hops[path->path_length - 1].out_port->sw),
> +		path->hops[path->path_length - 1].out_port->port);
> +	__tb_path_deactivate_hops(path, 0);
> +	__tb_path_deallocate_nfc(path, 0);
> +	path->activated = false;
> +}
> +
> +/**
> + * tb_path_activate() - activate a path
> + *
> + * Activate a path starting with the last hop and iterating backwards. The
> + * caller must fill path->hops before calling tb_path_activate().
> + *
> + * Return: Returns 0 on success or an error code on failure.
> + */
> +int tb_path_activate(struct tb_path *path)
> +{
> +	int i, res;
> +	enum tb_path_port out_mask, in_mask;
> +	if (path->activated) {
> +		tb_WARN(path->tb, "trying to activate already activated path\n");
> +		return -EINVAL;
> +	}
> +
> +	tb_info(path->tb,
> +		"activating path from %llx:%x to %llx:%x\n",
> +		tb_route(path->hops[0].in_port->sw),
> +		path->hops[0].in_port->port,
> +		tb_route(path->hops[path->path_length - 1].out_port->sw),
> +		path->hops[path->path_length - 1].out_port->port);
> +
> +	/* Clear counters. */
> +	for (i = path->path_length - 1; i >= 0; i--) {
> +		if (path->hops[i].in_counter_index == -1)
> +			continue;
> +		res = tb_port_clear_counter(path->hops[i].in_port,
> +					    path->hops[i].in_counter_index);
> +		if (res)
> +			goto err;
> +	}
> +
> +	/* Add non flow controlled credits. */
> +	for (i = path->path_length - 1; i >= 0; i--) {
> +		res = tb_port_add_nfc_credits(path->hops[i].in_port,
> +					      path->nfc_credits);
> +		if (res) {
> +			__tb_path_deallocate_nfc(path, i);
> +			goto err;
> +		}
> +	}
> +
> +	/* Activate hops. */
> +	for (i = path->path_length - 1; i >= 0; i--) {
> +		struct tb_regs_hop hop;
> +
> +		/* dword 0 */
> +		hop.next_hop = path->hops[i].next_hop_index;
> +		hop.out_port = path->hops[i].out_port->port;
> +		/* TODO: figure out why these are good values */
> +		hop.initial_credits = (i == path->path_length - 1) ? 16 : 7;
> +		hop.unknown1 = 0;
> +		hop.enable = 1;
> +
> +		/* dword 1 */
> +		out_mask = (i == path->path_length - 1) ?
> +				TB_PATH_DESTINATION : TB_PATH_INTERNAL;
> +		in_mask = (i == 0) ? TB_PATH_SOURCE : TB_PATH_INTERNAL;
> +		hop.weight = path->weight;
> +		hop.unknown2 = 0;
> +		hop.priority = path->priority;
> +		hop.drop_packages = path->drop_packages;
> +		hop.counter = path->hops[i].in_counter_index;
> +		hop.counter_enable = path->hops[i].in_counter_index != -1;
> +		hop.ingress_fc = path->ingress_fc_enable & in_mask;
> +		hop.egress_fc = path->egress_fc_enable & out_mask;
> +		hop.ingress_shared_buffer = path->ingress_shared_buffer
> +					    & in_mask;
> +		hop.egress_shared_buffer = path->egress_shared_buffer
> +					    & out_mask;
> +		hop.unknown3 = 0;
> +
> +		tb_port_info(path->hops[i].in_port, "Writing hop %d, index %d",
> +			     i, path->hops[i].in_hop_index);
> +		tb_dump_hop(path->hops[i].in_port, &hop);
> +		res = tb_port_write(path->hops[i].in_port, &hop, TB_CFG_HOPS,
> +				    2 * path->hops[i].in_hop_index, 2);
> +		if (res) {
> +			__tb_path_deactivate_hops(path, i);
> +			__tb_path_deallocate_nfc(path, 0);
> +			goto err;
> +		}
> +	}
> +	path->activated = true;
> +	tb_info(path->tb, "path activation complete\n");
> +	return 0;
> +err:
> +	tb_WARN(path->tb, "path activation failed\n");
> +	return res;
> +}
> +
> +/**
> + * tb_path_is_invalid() - check whether any ports on the path are invalid
> + *
> + * Return: Returns true if the path is invalid, false otherwise.
> + */
> +bool tb_path_is_invalid(struct tb_path *path)
> +{
> +	int i = 0;
> +	for (i = 0; i < path->path_length; i++) {
> +		if (path->hops[i].in_port->sw->is_unplugged)
> +			return true;
> +		if (path->hops[i].out_port->sw->is_unplugged)
> +			return true;
> +	}
> +	return false;
> +}
> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> index c092f7c..a6968cc 100644
> --- a/drivers/thunderbolt/switch.c
> +++ b/drivers/thunderbolt/switch.c
> @@ -139,6 +139,40 @@ int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged)
>  }
>  
>  /**
> + * tb_port_add_nfc_credits() - add/remove non flow controlled credits to port
> + *
> + * Change the number of NFC credits allocated to @port by @credits. To remove
> + * NFC credits pass a negative amount of credits.
> + *
> + * Return: Returns 0 on success or an error code on failure.
> + */
> +int tb_port_add_nfc_credits(struct tb_port *port, int credits)
> +{
> +	if (credits == 0)
> +		return 0;
> +	tb_port_info(port,
> +		     "adding %#x NFC credits (%#x -> %#x)",
> +		     credits,
> +		     port->config.nfc_credits,
> +		     port->config.nfc_credits + credits);
> +	port->config.nfc_credits += credits;
> +	return tb_port_write(port, &port->config.nfc_credits,
> +			     TB_CFG_PORT, 4, 1);
> +}
> +
> +/**
> + * tb_port_clear_counter() - clear a counter in TB_CFG_COUNTER
> + *
> + * Return: Returns 0 on success or an error code on failure.
> + */
> +int tb_port_clear_counter(struct tb_port *port, int counter)
> +{
> +	u32 zero[3] = { 0, 0, 0 };
> +	tb_port_info(port, "clearing counter %d\n", counter);
> +	return tb_port_write(port, zero, TB_CFG_COUNTERS, 3 * counter, 3);
> +}
> +
> +/**
>   * tb_init_port() - initialize a port
>   *
>   * This is a helper method for tb_switch_alloc. Does not check or initialize
> diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
> index 661f182..8bbdc2b 100644
> --- a/drivers/thunderbolt/tb.h
> +++ b/drivers/thunderbolt/tb.h
> @@ -35,6 +35,60 @@ struct tb_port {
>  };
>  
>  /**
> + * struct tb_path_hop - routing information for a tb_path
> + *
> + * Hop configuration is always done on the IN port of a switch.
> + * in_port and out_port have to be on the same switch. Packets arriving on
> + * in_port with "hop" = in_hop_index will get routed to through out_port. The
> + * next hop to take (on out_port->remote) is determined by next_hop_index.
> + *
> + * in_counter_index is the index of a counter (in TB_CFG_COUNTERS) on the in
> + * port.
> + */
> +struct tb_path_hop {
> +	struct tb_port *in_port;
> +	struct tb_port *out_port;
> +	int in_hop_index;
> +	int in_counter_index; /* write -1 to disable counters for this hop. */
> +	int next_hop_index;
> +};
> +
> +/**
> + * enum tb_path_port - path options mask
> + */
> +enum tb_path_port {
> +	TB_PATH_NONE = 0,
> +	TB_PATH_SOURCE = 1, /* activate on the first hop (out of src) */
> +	TB_PATH_INTERNAL = 2, /* activate on other hops (not the first/last) */
> +	TB_PATH_DESTINATION = 4, /* activate on the last hop (into dst) */
> +	TB_PATH_ALL = 7,
> +};
> +
> +/**
> + * struct tb_path - a unidirectional path between two ports
> + *
> + * A path consists of a number of hops (see tb_path_hop). To establish a PCIe
> + * tunnel two paths have to be created between the two PCIe ports.
> + *
> + */
> +struct tb_path {
> +	struct tb *tb;
> +	int nfc_credits; /* non flow controlled credits */
> +	enum tb_path_port ingress_shared_buffer;
> +	enum tb_path_port egress_shared_buffer;
> +	enum tb_path_port ingress_fc_enable;
> +	enum tb_path_port egress_fc_enable;
> +
> +	int priority:3;
> +	int weight:4;
> +	bool drop_packages;
> +	bool activated;
> +	struct tb_path_hop *hops;
> +	int path_length; /* number of hops */
> +};
> +
> +
> +/**
>   * struct tb - main thunderbolt bus structure
>   */
>  struct tb {
> @@ -165,9 +219,17 @@ void tb_sw_set_unpplugged(struct tb_switch *sw);
>  struct tb_switch *get_switch_at_route(struct tb_switch *sw, u64 route);
>  
>  int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged);
> +int tb_port_add_nfc_credits(struct tb_port *port, int credits);
> +int tb_port_clear_counter(struct tb_port *port, int counter);
>  
>  int tb_find_cap(struct tb_port *port, enum tb_cfg_space space, u32 value);
>  
> +struct tb_path *tb_path_alloc(struct tb *tb, int num_hops);
> +void tb_path_free(struct tb_path *path);
> +int tb_path_activate(struct tb_path *path);
> +void tb_path_deactivate(struct tb_path *path);
> +bool tb_path_is_invalid(struct tb_path *path);
> +
>  
>  static inline int tb_route_length(u64 route)
>  {
> -- 
> 1.9.3
>