On Thu, Apr 10, 2014 at 06:56:49PM +0200, Andrew Jones wrote:
> Add some device tree functions, built on libfdt, to the arch-neutral
> lib code in order to facilitate the extraction of boot info and device
> base addresses. These functions should work on device trees conforming
> to section III of the kernel doc
> Documentation/devicetree/booting-without-of.txt.
>
> Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
> ---
> v4: reworked everything, added lots of comments to devicetree.h
=> reworked everything
that will make it easy to review again ;)
> ---
> lib/devicetree.c | 289 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> lib/devicetree.h | 230 +++++++++++++++++++++++++++++++++++++++++++
> lib/libcflat.h | 2 +
> 3 files changed, 521 insertions(+)
> create mode 100644 lib/devicetree.c
> create mode 100644 lib/devicetree.h
>
> diff --git a/lib/devicetree.c b/lib/devicetree.c
> new file mode 100644
> index 0000000000000..482028f066346
> --- /dev/null
> +++ b/lib/devicetree.c
> @@ -0,0 +1,289 @@
> +/*
> + * Copyright (C) 2014, Red Hat Inc, Andrew Jones <drjones@xxxxxxxxxx>
> + *
> + * This work is licensed under the terms of the GNU LGPL, version 2.
> + */
> +#include "libcflat.h"
> +#include "libfdt/libfdt.h"
> +#include "devicetree.h"
> +
> +static const void *fdt;
> +static u32 root_nr_address_cells, root_nr_size_cells;
> +
> +const void *dt_fdt(void)
> +{
> + return fdt;
> +}
> +
> +bool dt_available(void)
> +{
> + return fdt_check_header(fdt) == 0;
> +}
> +
> +int dt_get_nr_cells(int fdtnode, u32 *nr_address_cells, u32 *nr_size_cells)
> +{
> + const struct fdt_property *prop;
> + u32 *nr_cells;
> + int len;
> +
> + prop = fdt_get_property(fdt, fdtnode, "#address-cells", &len);
> + if (prop == NULL)
> + return len;
> +
> + nr_cells = (u32 *)prop->data;
> + *nr_address_cells = fdt32_to_cpu(*nr_cells);
> +
> + prop = fdt_get_property(fdt, fdtnode, "#size-cells", &len);
> + if (prop == NULL)
> + return len;
> +
> + nr_cells = (u32 *)prop->data;
> + *nr_size_cells = fdt32_to_cpu(*nr_cells);
> +
> + return 0;
> +}
> +
> +void dt_reg_init(struct dt_reg *reg, u32 nr_address_cells, u32 nr_size_cells)
> +{
> + memset(reg, 0, sizeof(struct dt_reg));
> + reg->nr_address_cells = nr_address_cells;
> + reg->nr_size_cells = nr_size_cells;
> +}
> +
> +int dt_get_reg(int fdtnode, int regidx, struct dt_reg *reg)
> +{
> + const struct fdt_property *prop;
> + u32 *cells, i;
> + unsigned nr_tuple_cells;
> + int len;
> +
> + prop = fdt_get_property(fdt, fdtnode, "reg", &len);
> + if (prop == NULL)
> + return len;
> +
> + cells = (u32 *)prop->data;
> + nr_tuple_cells = reg->nr_address_cells + reg->nr_size_cells;
> + regidx *= nr_tuple_cells;
> +
> + if (regidx + nr_tuple_cells > len/sizeof(u32))
Shouldn't this be >= ?
> + return -FDT_ERR_NOTFOUND;
> +
> + for (i = 0; i < reg->nr_address_cells; ++i)
> + reg->address_cells[i] = fdt32_to_cpu(cells[regidx + i]);
> +
> + regidx += reg->nr_address_cells;
> + for (i = 0; i < reg->nr_size_cells; ++i)
> + reg->size_cells[i] = fdt32_to_cpu(cells[regidx + i]);
> +
> + return 0;
> +}
> +
> +int dt_pbus_translate_node(int fdtnode, int regidx, void *reg)
why doesn't this function take a struct dt_pbus_reg * instead of a
void *?
> +{
> + struct dt_pbus_reg *pbus_reg = (struct dt_pbus_reg *)reg;
> + struct dt_reg raw_reg;
> + int ret;
> +
> + dt_reg_init(&raw_reg, root_nr_address_cells, root_nr_size_cells);
> +
> + ret = dt_get_reg(fdtnode, regidx, &raw_reg);
> + if (ret < 0)
> + return ret;
> +
> + pbus_reg->addr = dt_pbus_read_cells(raw_reg.nr_address_cells,
> + raw_reg.address_cells);
> + pbus_reg->size = dt_pbus_read_cells(raw_reg.nr_size_cells,
> + raw_reg.size_cells);
> +
> + return 0;
> +}
> +
> +int dt_pbus_translate(const struct dt_device *dev, int regidx,
> + void *reg)
> +{
> + return dt_pbus_translate_node(dev->fdtnode, regidx, reg);
> +}
> +
> +int dt_pbus_get_baseaddr(const struct dt_device *dev, dt_pbus_addr_t *base)
> +{
> + struct dt_pbus_reg reg;
> + int ret;
> +
> + ret = dt_pbus_translate(dev, 0, ®);
> + if (ret < 0)
> + return ret;
> +
> + *base = reg.addr;
> + return 0;
> +}
> +
> +int dt_bus_match_any(const struct dt_device *dev __unused, int fdtnode)
> +{
> + /* matches any device with a valid node */
> + return fdtnode < 0 ? fdtnode : 1;
> +}
> +
> +static const struct dt_bus dt_default_bus = {
> + .match = dt_bus_match_any,
> + .translate = dt_pbus_translate,
> +};
> +
> +void dt_bus_init_defaults(struct dt_bus *bus)
> +{
> + memcpy(bus, &dt_default_bus, sizeof(struct dt_bus));
> +}
> +
> +void dt_device_init(struct dt_device *dev, const struct dt_bus *bus,
> + const void *info)
> +{
> + memset(dev, 0, sizeof(struct dt_device));
> + dev->bus = bus;
> + dev->info = (void *)info;
> +}
> +
> +int dt_device_find_compatible(const struct dt_device *dev,
> + const char *compatible)
> +{
> + int node, ret;
> +
> + node = fdt_node_offset_by_compatible(fdt, -1, compatible);
> + while (node >= 0) {
> + ret = dev->bus->match(dev, node);
> + if (ret < 0)
> + return ret;
> + else if (ret)
> + break;
> + node = fdt_node_offset_by_compatible(fdt, node, compatible);
> + }
> + return node;
> +}
> +
> +int dt_pbus_get_baseaddr_compatible(const char *compatible,
> + dt_pbus_addr_t *baseaddr)
> +{
> + struct dt_device dev;
> + int node, ret;
> +
> + dt_device_init(&dev, &dt_default_bus, NULL);
> +
> + node = dt_device_find_compatible(&dev, compatible);
> + if (node < 0)
> + return node;
> +
> + dt_device_bind_node(&dev, node);
> +
> + ret = dt_pbus_get_baseaddr(&dev, baseaddr);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> +}
> +
> +int dt_get_memory_params(struct dt_pbus_reg *regs, int nr_regs)
> +{
> + const char *pn = "device_type", *pv = "memory";
> + int node, ret, pl = strlen(pv) + 1, nr = 0;
> + struct dt_pbus_reg reg;
> +
> + node = fdt_node_offset_by_prop_value(fdt, -1, pn, pv, pl);
> +
> + while (node >= 0) {
> +
> + while (nr < nr_regs) {
> + ret = dt_pbus_translate_node(node, nr, ®);
> + if (ret == -FDT_ERR_NOTFOUND)
> + break;
> + if (ret < 0)
> + return ret;
> + regs[nr].addr = reg.addr;
> + regs[nr].size = reg.size;
> + ++nr;
> + }
> +
> + node = fdt_node_offset_by_prop_value(fdt, node, pn, pv, pl);
> + }
> +
> + return node != -FDT_ERR_NOTFOUND ? node : nr;
> +}
> +
> +int dt_for_each_cpu_node(void (*func)(int fdtnode, u32 regval, void *info),
> + void *info)
> +{
> + const struct fdt_property *prop;
> + int cpus, cpu, ret, len;
> + struct dt_reg raw_reg;
> + u32 nac, nsc;
> +
> + cpus = fdt_path_offset(fdt, "/cpus");
> + if (cpus < 0)
> + return cpus;
> +
> + ret = dt_get_nr_cells(cpus, &nac, &nsc);
> + if (ret < 0)
> + return ret;
> +
> + dt_reg_init(&raw_reg, nac, nsc);
> +
> + dt_for_each_subnode(cpus, cpu) {
> +
> + prop = fdt_get_property(fdt, cpu, "device_type", &len);
> + if (prop == NULL)
> + return len;
> +
> + if (len != 4 || strcmp((char *)prop->data, "cpu"))
> + continue;
> +
> + ret = dt_get_reg(cpu, 0, &raw_reg);
> + if (ret < 0)
> + return ret;
> +
> + func(cpu, raw_reg.address_cells[0], info);
> + }
> +
> + return 0;
> +}
> +
> +int dt_get_bootargs(const char **bootargs)
> +{
> + const struct fdt_property *prop;
> + int node, len;
> +
> + *bootargs = NULL;
> +
> + node = fdt_path_offset(fdt, "/chosen");
> + if (node < 0)
> + return node;
> +
> + prop = fdt_get_property(fdt, node, "bootargs", &len);
> + if (prop)
> + *bootargs = (char *)prop->data;
> + else if (len < 0 && len != -FDT_ERR_NOTFOUND)
> + return len;
so if you get FDT_ERR_NOTFOUND you still return success but the bootargs
won't be set? why?
> +
> + return 0;
> +}
> +
> +int dt_init(const void *fdt_ptr)
> +{
> + struct dt_bus *defbus = (struct dt_bus *)&dt_default_bus;
> + int root, ret;
> +
> + ret = fdt_check_header(fdt_ptr);
> + if (ret < 0)
> + return ret;
> + fdt = fdt_ptr;
> +
> + root = fdt_path_offset(fdt, "/");
> + if (root < 0)
> + return root;
> +
> + ret = dt_get_nr_cells(root, &root_nr_address_cells,
> + &root_nr_size_cells);
> + if (ret < 0)
> + return ret;
> +
> + defbus->nr_address_cells = root_nr_address_cells;
> + defbus->nr_size_cells = root_nr_size_cells;
> +
> + return 0;
> +}
> diff --git a/lib/devicetree.h b/lib/devicetree.h
> new file mode 100644
> index 0000000000000..032b5497f9db1
> --- /dev/null
> +++ b/lib/devicetree.h
> @@ -0,0 +1,230 @@
> +#ifndef _DEVICETREE_H_
> +#define _DEVICETREE_H_
> +/*
> + * devicetree builds on libfdt to implement abstractions and accessors
> + * for Linux required device tree content. The accessors provided are
> + * common across architectures. See section III of the kernel doc
> + * Documentation/devicetree/booting-without-of.txt
> + *
> + * Copyright (C) 2014, Red Hat Inc, Andrew Jones <drjones@xxxxxxxxxx>
> + *
> + * This work is licensed under the terms of the GNU LGPL, version 2.
> + */
> +#include "libcflat.h"
> +#include "libfdt/libfdt.h"
> +
> +/**********************************************************************
> + * devicetree init and libfdt helpers
> + **********************************************************************/
> +
> +/* dt_init initializes devicetree with a pointer to an fdt, @fdt_ptr */
> +extern int dt_init(const void *fdt_ptr);
> +
> +/* get the fdt pointer that devicetree is using */
> +const void *dt_fdt(void);
nit: why no extern here?
> +
> +/* check for an initialized, valid devicetree */
> +extern bool dt_available(void);
> +
> +/* traverse child nodes */
> +#define dt_for_each_subnode(n, s) \
> + for (s = fdt_first_subnode(dt_fdt(), n); \
> + s != -FDT_ERR_NOTFOUND; \
> + s = fdt_next_subnode(dt_fdt(), s))
> +
> +/**********************************************************************
> + * Abstractions for required node types and properties
> + **********************************************************************/
> +
> +struct dt_device {
> + int fdtnode;
> + const struct dt_bus *bus;
> +
> + /*
> + * info is a pointer to device specific data, which may be
> + * used by the bus match() and translate() functions
> + */
> + void *info;
> +};
> +
> +struct dt_bus {
> + /*
> + * match a device @dev to an fdt node @fdtnode
> + * returns
> + * - a positive value on match
> + * - zero on no match
> + * - a negative FDT_ERR_* value on failure
> + */
> + int (*match)(const struct dt_device *dev, int fdtnode);
> +
> + /*
> + * translate the @regidx'th "address size" tuple of
> + * @dev's fdt node's "reg" property, and store the result
> + * in @reg, a bus specific structure
> + * returns
> + * - zero on success
> + * - a negative FDT_ERR_* value on failure
> + */
> + int (*translate)(const struct dt_device *dev, int regidx, void *reg);
> +
> + /* the bus #address-cells and #size-cells properties */
> + u32 nr_address_cells, nr_size_cells;
> +};
> +
> +/* dt_bus_match_any matches any fdt node, i.e. it always returns true */
> +extern int dt_bus_match_any(const struct dt_device *dev, int fdtnode);
> +
> +/* the processor bus (pbus) address type and register tuple */
> +typedef u64 dt_pbus_addr_t;
> +struct dt_pbus_reg {
> + dt_pbus_addr_t addr;
> + dt_pbus_addr_t size;
> +};
> +
> +static inline dt_pbus_addr_t dt_pbus_read_cells(u32 nr_cells, u32 *cells)
> +{
> + return nr_cells == 2 ? ((u64)cells[0] << 32) | cells[1]
> + : nr_cells == 1 ? cells[0] : (~0ULL);
Why the tertiary operator here? A simple if or select statement should
make the code much easier to read and you don't seem to handle
#address-cells == 4or #size-cells == 4, despite the fact that you define
MAX_ADDRESS_CELLS=4 etc. This seems a bit weird to me.
> +}
> +
> +/*
> + * dt_pbus_translate translates device node regs for the
> + * processor bus using the root node's #address-cells and
> + * #size-cells and dt_pbus_read_cells()
> + * returns
> + * - zero on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_pbus_translate(const struct dt_device *dev, int regidx,
> + void *reg);
> +
> +/*
> + * dt_pbus_translate_node is the same as dt_pbus_translate but
> + * operates on an fdt node instead of a dt_device
> + */
> +extern int dt_pbus_translate_node(int fdtnode, int regidx, void *reg);
> +
> +/*
> + * dt_pbus_get_baseaddr is a shortcut for
> + * dt_pbus_translate(dev, 0, ®);
> + * *base = reg.addr;
> + * returns
> + * - zero on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_pbus_get_baseaddr(const struct dt_device *dev,
> + dt_pbus_addr_t *base);
> +
> +/*
> + * dt_bus_init_defaults initializes @bus with
> + * match <- dt_bus_match_any
> + * translate <- dt_pbus_translate
> + * nr_address_cells <- #address-cells of the root node
> + * nr_size_cells <- #size-cells of the root node
> + */
> +extern void dt_bus_init_defaults(struct dt_bus *bus);
> +
> +/*
> + * dt_device_init initializes a dt_device with the given parameters
> + */
> +extern void dt_device_init(struct dt_device *dev, const struct dt_bus *bus,
> + const void *info);
> +
> +static inline void dt_device_bind_node(struct dt_device *dev, int fdtnode)
> +{
> + dev->fdtnode = fdtnode;
> +}
> +
> +/*
> + * dt_device_find_compatible finds a @compatible node
> + * returns
> + * - node (>= 0) on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_device_find_compatible(const struct dt_device *dev,
> + const char *compatible);
> +
> +/*
> + * dt_pbus_get_baseaddr_compatible simply bundles many functions into
> + * one. It finds the first @compatible fdt node and then translates the
> + * 0th reg tuple (the base address) using the processor bus translation,
> + * and finally stores that address in @baseaddr.
> + * returns
> + * - zero on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_pbus_get_baseaddr_compatible(const char *compatible,
> + dt_pbus_addr_t *baseaddr);
> +
> +/**********************************************************************
> + * Low-level accessors for required node types and properties
> + **********************************************************************/
> +
> +/*
> + * dt_get_nr_cells sets @nr_address_cells and @nr_size_cells to the
> + * #address-cells and #size-cells properties of @fdtnode
> + * returns
> + * - zero on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_get_nr_cells(int fdtnode, u32 *nr_address_cells,
> + u32 *nr_size_cells);
> +
> +/* dt_reg is a structure for "raw" reg tuples */
> +#define MAX_ADDRESS_CELLS 4
> +#define MAX_SIZE_CELLS 4
> +struct dt_reg {
> + u32 nr_address_cells, nr_size_cells;
> + u32 address_cells[MAX_ADDRESS_CELLS];
> + u32 size_cells[MAX_SIZE_CELLS];
> +};
> +
> +/*
> + * dt_reg_init initialize a dt_reg struct to zero and sets
> + * nr_address_cells and nr_size_cells to @nr_address_cells and
> + * @nr_size_cells respectively.
> + */
> +extern void dt_reg_init(struct dt_reg *reg, u32 nr_address_cells,
> + u32 nr_size_cells);
> +
> +/*
> + * dt_get_reg gets the @regidx'th reg tuple of @fdtnode's reg property
> + * and stores it in @reg. @reg must be initialized.
> + * returns
> + * - zero on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_get_reg(int fdtnode, int regidx, struct dt_reg *reg);
> +
> +/**********************************************************************
> + * High-level accessors for required node types and properties
> + **********************************************************************/
> +
> +/*
> + * dt_get_bootargs gets a pointer to /chosen/bootargs
> + * returns
> + * - zero on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_get_bootargs(const char **bootargs);
> +
> +/*
> + * dt_get_memory_params gets the memory parameters from the /memory node(s)
> + * storing each memory region ("address size" tuple) in consecutive entries
> + * of @regs, up to @nr_regs
> + * returns
> + * - number of memory regions found on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_get_memory_params(struct dt_pbus_reg *regs, int nr_regs);
> +
> +/*
> + * dt_for_each_cpu_node runs @func on each cpu node in the /cpus node
> + * passing it its fdt node, its reg property value, and @info
> + * - zero on success
> + * - a negative FDT_ERR_* value on failure
> + */
> +extern int dt_for_each_cpu_node(void (*func)(int fdtnode, u32 regval,
> + void *info), void *info);
> +
> +#endif /* _DEVICETREE_H_ */
> diff --git a/lib/libcflat.h b/lib/libcflat.h
> index 76448a33cde5f..99d1cd533dd03 100644
> --- a/lib/libcflat.h
> +++ b/lib/libcflat.h
> @@ -22,6 +22,8 @@
>
> #include <stdarg.h>
>
> +#define __unused __attribute__((__unused__))
> +
> typedef unsigned char u8;
> typedef signed char s8;
> typedef unsigned short u16;
> --
> 1.8.1.4
>
-Christoffer
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