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320549a224
Commit 29bb45f25f (regmap-mmio: Use native endianness for read/write)
attempted to fix some long standing bugs in the MMIO implementation for
big endian systems caused by duplicate byte swapping in both regmap and
readl()/writel() which affected MIPS systems as when they are in big
endian mode they flip the endianness of all registers in the system, not
just the CPU. MIPS systems had worked around this by declaring regmap
using IPs as little endian which is inaccurate, unfortunately the issue
had not been reported.
Sadly the fix makes things worse rather than better. By changing the
behaviour to match the documentation it caused behaviour changes for
other IPs which broke them and by using the __raw I/O accessors to avoid
the endianness swapping in readl()/writel() it removed some memory
ordering guarantees and could potentially generate unvirtualisable
instructions on some architectures.
Unfortunately sorting out all this mess in any half way sensible fashion
was far too invasive to go in during an -rc cycle so instead let's go
back to the old broken behaviour for v4.5, the better fixes are already
queued for v4.6. This does mean that we keep the broken MIPS DTs for
another release but that seems the least bad way of handling the
situation.
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Mark Brown <broonie@kernel.org>
364 lines
7.6 KiB
C
364 lines
7.6 KiB
C
/*
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* Register map access API - MMIO support
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*
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* Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/regmap.h>
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#include <linux/slab.h>
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struct regmap_mmio_context {
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void __iomem *regs;
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unsigned val_bytes;
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struct clk *clk;
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void (*reg_write)(struct regmap_mmio_context *ctx,
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unsigned int reg, unsigned int val);
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unsigned int (*reg_read)(struct regmap_mmio_context *ctx,
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unsigned int reg);
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};
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static int regmap_mmio_regbits_check(size_t reg_bits)
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{
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switch (reg_bits) {
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case 8:
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case 16:
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case 32:
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#ifdef CONFIG_64BIT
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case 64:
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#endif
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return 0;
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default:
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return -EINVAL;
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}
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}
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static int regmap_mmio_get_min_stride(size_t val_bits)
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{
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int min_stride;
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switch (val_bits) {
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case 8:
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/* The core treats 0 as 1 */
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min_stride = 0;
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return 0;
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case 16:
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min_stride = 2;
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break;
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case 32:
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min_stride = 4;
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break;
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#ifdef CONFIG_64BIT
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case 64:
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min_stride = 8;
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break;
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#endif
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default:
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return -EINVAL;
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}
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return min_stride;
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}
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static void regmap_mmio_write8(struct regmap_mmio_context *ctx,
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unsigned int reg,
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unsigned int val)
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{
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writeb(val, ctx->regs + reg);
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}
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static void regmap_mmio_write16le(struct regmap_mmio_context *ctx,
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unsigned int reg,
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unsigned int val)
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{
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writew(val, ctx->regs + reg);
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}
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static void regmap_mmio_write16be(struct regmap_mmio_context *ctx,
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unsigned int reg,
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unsigned int val)
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{
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iowrite16be(val, ctx->regs + reg);
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}
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static void regmap_mmio_write32le(struct regmap_mmio_context *ctx,
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unsigned int reg,
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unsigned int val)
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{
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writel(val, ctx->regs + reg);
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}
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static void regmap_mmio_write32be(struct regmap_mmio_context *ctx,
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unsigned int reg,
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unsigned int val)
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{
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iowrite32be(val, ctx->regs + reg);
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}
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#ifdef CONFIG_64BIT
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static void regmap_mmio_write64le(struct regmap_mmio_context *ctx,
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unsigned int reg,
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unsigned int val)
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{
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writeq(val, ctx->regs + reg);
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}
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#endif
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static int regmap_mmio_write(void *context, unsigned int reg, unsigned int val)
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{
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struct regmap_mmio_context *ctx = context;
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int ret;
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if (!IS_ERR(ctx->clk)) {
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ret = clk_enable(ctx->clk);
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if (ret < 0)
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return ret;
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}
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ctx->reg_write(ctx, reg, val);
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if (!IS_ERR(ctx->clk))
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clk_disable(ctx->clk);
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return 0;
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}
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static unsigned int regmap_mmio_read8(struct regmap_mmio_context *ctx,
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unsigned int reg)
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{
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return readb(ctx->regs + reg);
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}
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static unsigned int regmap_mmio_read16le(struct regmap_mmio_context *ctx,
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unsigned int reg)
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{
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return readw(ctx->regs + reg);
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}
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static unsigned int regmap_mmio_read16be(struct regmap_mmio_context *ctx,
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unsigned int reg)
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{
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return ioread16be(ctx->regs + reg);
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}
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static unsigned int regmap_mmio_read32le(struct regmap_mmio_context *ctx,
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unsigned int reg)
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{
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return readl(ctx->regs + reg);
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}
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static unsigned int regmap_mmio_read32be(struct regmap_mmio_context *ctx,
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unsigned int reg)
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{
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return ioread32be(ctx->regs + reg);
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}
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#ifdef CONFIG_64BIT
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static unsigned int regmap_mmio_read64le(struct regmap_mmio_context *ctx,
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unsigned int reg)
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{
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return readq(ctx->regs + reg);
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}
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#endif
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static int regmap_mmio_read(void *context, unsigned int reg, unsigned int *val)
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{
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struct regmap_mmio_context *ctx = context;
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int ret;
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if (!IS_ERR(ctx->clk)) {
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ret = clk_enable(ctx->clk);
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if (ret < 0)
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return ret;
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}
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*val = ctx->reg_read(ctx, reg);
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if (!IS_ERR(ctx->clk))
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clk_disable(ctx->clk);
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return 0;
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}
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static void regmap_mmio_free_context(void *context)
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{
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struct regmap_mmio_context *ctx = context;
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if (!IS_ERR(ctx->clk)) {
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clk_unprepare(ctx->clk);
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clk_put(ctx->clk);
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}
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kfree(context);
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}
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static const struct regmap_bus regmap_mmio = {
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.fast_io = true,
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.reg_write = regmap_mmio_write,
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.reg_read = regmap_mmio_read,
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.free_context = regmap_mmio_free_context,
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};
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static struct regmap_mmio_context *regmap_mmio_gen_context(struct device *dev,
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const char *clk_id,
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void __iomem *regs,
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const struct regmap_config *config)
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{
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struct regmap_mmio_context *ctx;
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int min_stride;
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int ret;
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ret = regmap_mmio_regbits_check(config->reg_bits);
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if (ret)
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return ERR_PTR(ret);
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if (config->pad_bits)
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return ERR_PTR(-EINVAL);
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min_stride = regmap_mmio_get_min_stride(config->val_bits);
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if (min_stride < 0)
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return ERR_PTR(min_stride);
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if (config->reg_stride < min_stride)
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return ERR_PTR(-EINVAL);
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ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
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if (!ctx)
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return ERR_PTR(-ENOMEM);
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ctx->regs = regs;
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ctx->val_bytes = config->val_bits / 8;
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ctx->clk = ERR_PTR(-ENODEV);
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switch (config->reg_format_endian) {
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case REGMAP_ENDIAN_DEFAULT:
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case REGMAP_ENDIAN_LITTLE:
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#ifdef __LITTLE_ENDIAN
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case REGMAP_ENDIAN_NATIVE:
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#endif
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switch (config->val_bits) {
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case 8:
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ctx->reg_read = regmap_mmio_read8;
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ctx->reg_write = regmap_mmio_write8;
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break;
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case 16:
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ctx->reg_read = regmap_mmio_read16le;
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ctx->reg_write = regmap_mmio_write16le;
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break;
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case 32:
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ctx->reg_read = regmap_mmio_read32le;
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ctx->reg_write = regmap_mmio_write32le;
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break;
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#ifdef CONFIG_64BIT
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case 64:
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ctx->reg_read = regmap_mmio_read64le;
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ctx->reg_write = regmap_mmio_write64le;
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break;
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#endif
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default:
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ret = -EINVAL;
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goto err_free;
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}
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break;
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case REGMAP_ENDIAN_BIG:
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#ifdef __BIG_ENDIAN
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case REGMAP_ENDIAN_NATIVE:
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#endif
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switch (config->val_bits) {
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case 8:
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ctx->reg_read = regmap_mmio_read8;
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ctx->reg_write = regmap_mmio_write8;
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break;
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case 16:
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ctx->reg_read = regmap_mmio_read16be;
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ctx->reg_write = regmap_mmio_write16be;
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break;
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case 32:
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ctx->reg_read = regmap_mmio_read32be;
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ctx->reg_write = regmap_mmio_write32be;
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break;
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default:
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ret = -EINVAL;
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goto err_free;
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}
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break;
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default:
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ret = -EINVAL;
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goto err_free;
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}
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if (clk_id == NULL)
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return ctx;
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ctx->clk = clk_get(dev, clk_id);
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if (IS_ERR(ctx->clk)) {
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ret = PTR_ERR(ctx->clk);
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goto err_free;
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}
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ret = clk_prepare(ctx->clk);
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if (ret < 0) {
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clk_put(ctx->clk);
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goto err_free;
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}
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return ctx;
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err_free:
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kfree(ctx);
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return ERR_PTR(ret);
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}
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struct regmap *__regmap_init_mmio_clk(struct device *dev, const char *clk_id,
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void __iomem *regs,
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const struct regmap_config *config,
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struct lock_class_key *lock_key,
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const char *lock_name)
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{
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struct regmap_mmio_context *ctx;
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ctx = regmap_mmio_gen_context(dev, clk_id, regs, config);
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if (IS_ERR(ctx))
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return ERR_CAST(ctx);
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return __regmap_init(dev, ®map_mmio, ctx, config,
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lock_key, lock_name);
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}
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EXPORT_SYMBOL_GPL(__regmap_init_mmio_clk);
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struct regmap *__devm_regmap_init_mmio_clk(struct device *dev,
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const char *clk_id,
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void __iomem *regs,
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const struct regmap_config *config,
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struct lock_class_key *lock_key,
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const char *lock_name)
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{
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struct regmap_mmio_context *ctx;
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ctx = regmap_mmio_gen_context(dev, clk_id, regs, config);
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if (IS_ERR(ctx))
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return ERR_CAST(ctx);
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return __devm_regmap_init(dev, ®map_mmio, ctx, config,
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lock_key, lock_name);
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}
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EXPORT_SYMBOL_GPL(__devm_regmap_init_mmio_clk);
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MODULE_LICENSE("GPL v2");
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