--- /dev/null
+/*
+ * 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");
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff