crypto: caam - hwrng support

caam_read copies random bytes from two buffers into output.

caam rng can fill empty buffer 0xffff bytes at a time,
but the buffer sizes are rounded down to multiple of cacheline size.

Signed-off-by: Yuan Kang <Yuan.Kang@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

3 files changed, 323 insertions, 0 deletions

diff --git a/drivers/crypto/caam/Kconfig b/drivers/crypto/caam/Kconfig
index e61b7f50785e..502a7f3cca5f 100644
--- a/drivers/crypto/caam/Kconfig
+++ b/drivers/crypto/caam/Kconfig
@@ -82,3 +82,16 @@ config CRYPTO_DEV_FSL_CAAM_AHASH_API
 
           To compile this as a module, choose M here: the module
           will be called caamhash.
+
+config CRYPTO_DEV_FSL_CAAM_RNG_API
+        tristate "Register caam device for hwrng API"
+        depends on CRYPTO_DEV_FSL_CAAM
+        default y
+        select CRYPTO_RNG
+        select HW_RANDOM
+        help
+          Selecting this will register the SEC4 hardware rng to
+          the hw_random API for suppying the kernel entropy pool.
+
+          To compile this as a module, choose M here: the module
+          will be called caamrng.
diff --git a/drivers/crypto/caam/Makefile b/drivers/crypto/caam/Makefile
index 9ef1cb00c342..b1eb44838db5 100644
--- a/drivers/crypto/caam/Makefile
+++ b/drivers/crypto/caam/Makefile
@@ -5,5 +5,6 @@
 obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM) += caam.o
 obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API) += caamalg.o
 obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_AHASH_API) += caamhash.o
+obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_API) += caamrng.o
 
 caam-objs := ctrl.o jr.o error.o key_gen.o
diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c
new file mode 100644
index 000000000000..e2bfe161dece
--- /dev/null
+++ b/drivers/crypto/caam/caamrng.c
@@ -0,0 +1,309 @@
+/*
+ * caam - Freescale FSL CAAM support for hw_random
+ *
+ * Copyright 2011 Freescale Semiconductor, Inc.
+ *
+ * Based on caamalg.c crypto API driver.
+ *
+ * relationship between job descriptors to shared descriptors:
+ *
+ * ---------------                     --------------
+ * | JobDesc #0  |-------------------->| ShareDesc  |
+ * | *(buffer 0) |      |------------->| (generate) |
+ * ---------------      |              | (move)     |
+ *                      |              | (store)    |
+ * ---------------      |              --------------
+ * | JobDesc #1  |------|
+ * | *(buffer 1) |
+ * ---------------
+ *
+ * A job desc looks like this:
+ *
+ * ---------------------
+ * | Header            |
+ * | ShareDesc Pointer |
+ * | SEQ_OUT_PTR       |
+ * | (output buffer)   |
+ * ---------------------
+ *
+ * The SharedDesc never changes, and each job descriptor points to one of two
+ * buffers for each device, from which the data will be copied into the
+ * requested destination
+ */
+
+#include <linux/hw_random.h>
+#include <linux/completion.h>
+#include <linux/atomic.h>
+
+#include "compat.h"
+
+#include "regs.h"
+#include "intern.h"
+#include "desc_constr.h"
+#include "jr.h"
+#include "error.h"
+
+/*
+ * Maximum buffer size: maximum number of random, cache-aligned bytes that
+ * will be generated and moved to seq out ptr (extlen not allowed)
+ */
+#define RN_BUF_SIZE                     (0xffff / L1_CACHE_BYTES * \
+                                         L1_CACHE_BYTES)
+
+/* length of descriptors */
+#define DESC_JOB_O_LEN                  (CAAM_CMD_SZ * 2 + CAAM_PTR_SZ * 2)
+#define DESC_RNG_LEN                    (10 * CAAM_CMD_SZ)
+
+/* Buffer, its dma address and lock */
+struct buf_data {
+        u8 buf[RN_BUF_SIZE];
+        dma_addr_t addr;
+        struct completion filled;
+        u32 hw_desc[DESC_JOB_O_LEN];
+#define BUF_NOT_EMPTY 0
+#define BUF_EMPTY 1
+#define BUF_PENDING 2  /* Empty, but with job pending --don't submit another */
+        atomic_t empty;
+};
+
+/* rng per-device context */
+struct caam_rng_ctx {
+        struct device *jrdev;
+        dma_addr_t sh_desc_dma;
+        u32 sh_desc[DESC_RNG_LEN];
+        unsigned int cur_buf_idx;
+        int current_buf;
+        struct buf_data bufs[2];
+};
+
+static struct caam_rng_ctx rng_ctx;
+
+static inline void rng_unmap_buf(struct device *jrdev, struct buf_data *bd)
+{
+        if (bd->addr)
+                dma_unmap_single(jrdev, bd->addr, RN_BUF_SIZE,
+                                 DMA_FROM_DEVICE);
+}
+
+static inline void rng_unmap_ctx(struct caam_rng_ctx *ctx)
+{
+        struct device *jrdev = ctx->jrdev;
+
+        if (ctx->sh_desc_dma)
+                dma_unmap_single(jrdev, ctx->sh_desc_dma, DESC_RNG_LEN,
+                                 DMA_TO_DEVICE);
+        rng_unmap_buf(jrdev, &ctx->bufs[0]);
+        rng_unmap_buf(jrdev, &ctx->bufs[1]);
+}
+
+static void rng_done(struct device *jrdev, u32 *desc, u32 err, void *context)
+{
+        struct buf_data *bd;
+
+        bd = (struct buf_data *)((char *)desc -
+              offsetof(struct buf_data, hw_desc));
+
+        if (err) {
+                char tmp[CAAM_ERROR_STR_MAX];
+
+                dev_err(jrdev, "%08x: %s\n", err, caam_jr_strstatus(tmp, err));
+        }
+
+        atomic_set(&bd->empty, BUF_NOT_EMPTY);
+        complete(&bd->filled);
+#ifdef DEBUG
+        print_hex_dump(KERN_ERR, "rng refreshed buf@: ",
+                       DUMP_PREFIX_ADDRESS, 16, 4, bd->buf, RN_BUF_SIZE, 1);
+#endif
+}
+
+static inline int submit_job(struct caam_rng_ctx *ctx, int to_current)
+{
+        struct buf_data *bd = &ctx->bufs[!(to_current ^ ctx->current_buf)];
+        struct device *jrdev = ctx->jrdev;
+        u32 *desc = bd->hw_desc;
+        int err;
+
+        dev_dbg(jrdev, "submitting job %d\n", !(to_current ^ ctx->current_buf));
+        init_completion(&bd->filled);
+        err = caam_jr_enqueue(jrdev, desc, rng_done, ctx);
+        if (err)
+                complete(&bd->filled); /* don't wait on failed job*/
+        else
+                atomic_inc(&bd->empty); /* note if pending */
+
+        return err;
+}
+
+static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+        struct caam_rng_ctx *ctx = &rng_ctx;
+        struct buf_data *bd = &ctx->bufs[ctx->current_buf];
+        int next_buf_idx, copied_idx;
+        int err;
+
+        if (atomic_read(&bd->empty)) {
+                /* try to submit job if there wasn't one */
+                if (atomic_read(&bd->empty) == BUF_EMPTY) {
+                        err = submit_job(ctx, 1);
+                        /* if can't submit job, can't even wait */
+                        if (err)
+                                return 0;
+                }
+                /* no immediate data, so exit if not waiting */
+                if (!wait)
+                        return 0;
+
+                /* waiting for pending job */
+                if (atomic_read(&bd->empty))
+                        wait_for_completion(&bd->filled);
+        }
+
+        next_buf_idx = ctx->cur_buf_idx + max;
+        dev_dbg(ctx->jrdev, "%s: start reading at buffer %d, idx %d\n",
+                 __func__, ctx->current_buf, ctx->cur_buf_idx);
+
+        /* if enough data in current buffer */
+        if (next_buf_idx < RN_BUF_SIZE) {
+                memcpy(data, bd->buf + ctx->cur_buf_idx, max);
+                ctx->cur_buf_idx = next_buf_idx;
+                return max;
+        }
+
+        /* else, copy what's left... */
+        copied_idx = RN_BUF_SIZE - ctx->cur_buf_idx;
+        memcpy(data, bd->buf + ctx->cur_buf_idx, copied_idx);
+        ctx->cur_buf_idx = 0;
+        atomic_set(&bd->empty, BUF_EMPTY);
+
+        /* ...refill... */
+        submit_job(ctx, 1);
+
+        /* and use next buffer */
+        ctx->current_buf = !ctx->current_buf;
+        dev_dbg(ctx->jrdev, "switched to buffer %d\n", ctx->current_buf);
+
+        /* since there already is some data read, don't wait */
+        return copied_idx + caam_read(rng, data + copied_idx,
+                                      max - copied_idx, false);
+}
+
+static inline void rng_create_sh_desc(struct caam_rng_ctx *ctx)
+{
+        struct device *jrdev = ctx->jrdev;
+        u32 *desc = ctx->sh_desc;
+
+        init_sh_desc(desc, HDR_SHARE_WAIT);
+
+        /* Propagate errors from shared to job descriptor */
+        append_cmd(desc, SET_OK_NO_PROP_ERRORS | CMD_LOAD);
+
+        /* Generate random bytes */
+        append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG);
+
+        /* Store bytes */
+        append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE);
+
+        ctx->sh_desc_dma = dma_map_single(jrdev, desc, desc_bytes(desc),
+                                          DMA_TO_DEVICE);
+#ifdef DEBUG
+        print_hex_dump(KERN_ERR, "rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
+                       desc, desc_bytes(desc), 1);
+#endif
+}
+
+static inline void rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id)
+{
+        struct device *jrdev = ctx->jrdev;
+        struct buf_data *bd = &ctx->bufs[buf_id];
+        u32 *desc = bd->hw_desc;
+        int sh_len = desc_len(ctx->sh_desc);
+
+        init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len, HDR_SHARE_DEFER |
+                             HDR_REVERSE);
+
+        bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE, DMA_FROM_DEVICE);
+
+        append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0);
+#ifdef DEBUG
+        print_hex_dump(KERN_ERR, "rng job desc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
+                       desc, desc_bytes(desc), 1);
+#endif
+}
+
+static void caam_cleanup(struct hwrng *rng)
+{
+        int i;
+        struct buf_data *bd;
+
+        for (i = 0; i < 2; i++) {
+                bd = &rng_ctx.bufs[i];
+                if (atomic_read(&bd->empty) == BUF_PENDING)
+                        wait_for_completion(&bd->filled);
+        }
+
+        rng_unmap_ctx(&rng_ctx);
+}
+
+static void caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
+{
+        struct buf_data *bd = &ctx->bufs[buf_id];
+
+        rng_create_job_desc(ctx, buf_id);
+        atomic_set(&bd->empty, BUF_EMPTY);
+        submit_job(ctx, buf_id == ctx->current_buf);
+        wait_for_completion(&bd->filled);
+}
+
+static void caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev)
+{
+        ctx->jrdev = jrdev;
+        rng_create_sh_desc(ctx);
+        ctx->current_buf = 0;
+        ctx->cur_buf_idx = 0;
+        caam_init_buf(ctx, 0);
+        caam_init_buf(ctx, 1);
+}
+
+static struct hwrng caam_rng = {
+        .name           = "rng-caam",
+        .cleanup        = caam_cleanup,
+        .read           = caam_read,
+};
+
+static void __exit caam_rng_exit(void)
+{
+        hwrng_unregister(&caam_rng);
+}
+
+static int __init caam_rng_init(void)
+{
+        struct device_node *dev_node;
+        struct platform_device *pdev;
+        struct device *ctrldev;
+        struct caam_drv_private *priv;
+
+        dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec-v4.0");
+        if (!dev_node)
+                return -ENODEV;
+
+        pdev = of_find_device_by_node(dev_node);
+        if (!pdev)
+                return -ENODEV;
+
+        ctrldev = &pdev->dev;
+        priv = dev_get_drvdata(ctrldev);
+        of_node_put(dev_node);
+
+        caam_init_rng(&rng_ctx, priv->jrdev[0]);
+
+        dev_info(priv->jrdev[0], "registering rng-caam\n");
+        return hwrng_register(&caam_rng);
+}
+
+module_init(caam_rng_init);
+module_exit(caam_rng_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("FSL CAAM support for hw_random API");
+MODULE_AUTHOR("Freescale Semiconductor - NMG");