]> git.kernelconcepts.de Git - karo-tx-uboot.git/blobdiff - arch/arm/cpu/armv7/mx5/clock.c
karo: merge with Ka-Ro specific tree for secure boot support
[karo-tx-uboot.git] / arch / arm / cpu / armv7 / mx5 / clock.c
index bf52f0d19e546e0b98b2717b25618c4c6711e92b..443fb997826244080a4dd3d4ce7a1a979ee1e802 100644 (file)
@@ -46,15 +46,14 @@ struct mxc_pll_reg *mxc_plls[PLL_CLOCKS] = {
 #define EMI_DIV_MAX     8
 #define NFC_DIV_MAX     8
 
-#define MX5_CBCMR      0x00015154
-#define MX5_CBCDR      0x02888945
+#define MXC_IPG_PER_CLK        MXC_IPG_PERCLK
 
 struct fixed_pll_mfd {
        u32 ref_clk_hz;
        u32 mfd;
 };
 
-const struct fixed_pll_mfd fixed_mfd[] = {
+static const struct fixed_pll_mfd fixed_mfd[] = {
        {MXC_HCLK, 24 * 16},
 };
 
@@ -67,12 +66,102 @@ struct pll_param {
 
 #define PLL_FREQ_MAX(ref_clk)  (4 * (ref_clk) * PLL_MFI_MAX)
 #define PLL_FREQ_MIN(ref_clk) \
-               ((2 * (ref_clk) * (PLL_MFI_MIN - 1)) / PLL_PD_MAX)
+       ((4 * (ref_clk) * PLL_MFI_MIN) / PLL_PD_MAX)
 #define MAX_DDR_CLK     420000000
 #define NFC_CLK_MAX     34000000
 
 struct mxc_ccm_reg *mxc_ccm = (struct mxc_ccm_reg *)MXC_CCM_BASE;
 
+int clk_enable(struct clk *clk)
+{
+       int ret = 0;
+
+       if (!clk)
+               return 0;
+
+       if (clk->usecount++ == 0) {
+               if (!clk->enable)
+                       return 0;
+               ret = clk->enable(clk);
+               if (ret)
+                       clk->usecount--;
+       }
+       return ret;
+}
+
+void clk_disable(struct clk *clk)
+{
+       if (!clk)
+               return;
+
+       if (!(--clk->usecount)) {
+               if (clk->disable)
+                       clk->disable(clk);
+       }
+       if (clk->usecount < 0) {
+               printf("%s: clk %p (%s) underflow\n", __func__, clk, clk->name);
+               hang();
+       }
+}
+
+int clk_get_usecount(struct clk *clk)
+{
+       if (clk == NULL)
+               return 0;
+
+       return clk->usecount;
+}
+
+u32 clk_get_rate(struct clk *clk)
+{
+       if (!clk)
+               return 0;
+
+       return clk->rate;
+}
+
+struct clk *clk_get_parent(struct clk *clk)
+{
+       if (!clk)
+               return 0;
+
+       return clk->parent;
+}
+
+int clk_set_rate(struct clk *clk, unsigned long rate)
+{
+       if (clk && clk->set_rate)
+               clk->set_rate(clk, rate);
+       return clk->rate;
+}
+
+long clk_round_rate(struct clk *clk, unsigned long rate)
+{
+       if (clk == NULL || !clk->round_rate)
+               return 0;
+
+       return clk->round_rate(clk, rate);
+}
+
+int clk_set_parent(struct clk *clk, struct clk *parent)
+{
+       debug("Setting parent of clk %p to %p (%p)\n", clk, parent,
+               clk ? clk->parent : NULL);
+
+       if (!clk || clk == parent)
+               return 0;
+
+       if (clk->set_parent) {
+               int ret;
+
+               ret = clk->set_parent(clk, parent);
+               if (ret)
+                       return ret;
+       }
+       clk->parent = parent;
+       return 0;
+}
+
 void set_usboh3_clk(void)
 {
        clrsetbits_le32(&mxc_ccm->cscmr1,
@@ -94,6 +183,100 @@ void enable_usboh3_clk(bool enable)
                        MXC_CCM_CCGR2_USBOH3_60M(cg));
 }
 
+void ipu_clk_enable(void)
+{
+       /* IPU root clock derived from AXI B */
+       clrsetbits_le32(&mxc_ccm->cbcmr, MXC_CCM_CBCMR_IPU_HSP_CLK_SEL_MASK,
+                       MXC_CCM_CBCMR_IPU_HSP_CLK_SEL(1));
+
+       setbits_le32(&mxc_ccm->CCGR5,
+               MXC_CCM_CCGR5_IPU(MXC_CCM_CCGR_CG_MASK));
+
+       /* Handshake with IPU when certain clock rates are changed. */
+       clrbits_le32(&mxc_ccm->ccdr, MXC_CCM_CCDR_IPU_HS_MASK);
+
+       /* Handshake with IPU when LPM is entered as its enabled. */
+       clrbits_le32(&mxc_ccm->clpcr, MXC_CCM_CLPCR_BYPASS_IPU_LPM_HS);
+}
+
+void ipu_clk_disable(void)
+{
+       clrbits_le32(&mxc_ccm->CCGR5,
+               MXC_CCM_CCGR5_IPU(MXC_CCM_CCGR_CG_MASK));
+
+       /* Handshake with IPU when certain clock rates are changed. */
+       setbits_le32(&mxc_ccm->ccdr, MXC_CCM_CCDR_IPU_HS_MASK);
+
+       /* Handshake with IPU when LPM is entered as its enabled. */
+       setbits_le32(&mxc_ccm->clpcr, MXC_CCM_CLPCR_BYPASS_IPU_LPM_HS);
+}
+
+void ipu_di_clk_enable(int di)
+{
+       switch (di) {
+       case 0:
+               setbits_le32(&mxc_ccm->CCGR6,
+                       MXC_CCM_CCGR6_IPU_DI0(MXC_CCM_CCGR_CG_MASK));
+               break;
+       case 1:
+               setbits_le32(&mxc_ccm->CCGR6,
+                       MXC_CCM_CCGR6_IPU_DI1(MXC_CCM_CCGR_CG_MASK));
+               break;
+       default:
+               printf("%s: Invalid DI index %d\n", __func__, di);
+       }
+}
+
+void ipu_di_clk_disable(int di)
+{
+       switch (di) {
+       case 0:
+               clrbits_le32(&mxc_ccm->CCGR6,
+                       MXC_CCM_CCGR6_IPU_DI0(MXC_CCM_CCGR_CG_MASK));
+               break;
+       case 1:
+               clrbits_le32(&mxc_ccm->CCGR6,
+                       MXC_CCM_CCGR6_IPU_DI1(MXC_CCM_CCGR_CG_MASK));
+               break;
+       default:
+               printf("%s: Invalid DI index %d\n", __func__, di);
+       }
+}
+
+#ifdef CONFIG_MX53
+void ldb_clk_enable(int ldb)
+{
+       switch (ldb) {
+       case 0:
+               setbits_le32(&mxc_ccm->CCGR6,
+                       MXC_CCM_CCGR6_LDB_DI0(MXC_CCM_CCGR_CG_MASK));
+               break;
+       case 1:
+               setbits_le32(&mxc_ccm->CCGR6,
+                       MXC_CCM_CCGR6_LDB_DI1(MXC_CCM_CCGR_CG_MASK));
+               break;
+       default:
+               printf("%s: Invalid LDB index %d\n", __func__, ldb);
+       }
+}
+
+void ldb_clk_disable(int ldb)
+{
+       switch (ldb) {
+       case 0:
+               clrbits_le32(&mxc_ccm->CCGR6,
+                       MXC_CCM_CCGR6_LDB_DI0(MXC_CCM_CCGR_CG_MASK));
+               break;
+       case 1:
+               clrbits_le32(&mxc_ccm->CCGR6,
+                       MXC_CCM_CCGR6_LDB_DI1(MXC_CCM_CCGR_CG_MASK));
+               break;
+       default:
+               printf("%s: Invalid LDB index %d\n", __func__, ldb);
+       }
+}
+#endif
+
 #ifdef CONFIG_SYS_I2C_MXC
 /* i2c_num can be from 0, to 1 for i.MX51 and 2 for i.MX53 */
 int enable_i2c_clk(unsigned char enable, unsigned i2c_num)
@@ -160,9 +343,10 @@ void enable_usb_phy2_clk(bool enable)
  */
 static uint32_t decode_pll(struct mxc_pll_reg *pll, uint32_t infreq)
 {
-       uint32_t ctrl, op, mfd, mfn, mfi, pdf, ret;
+       uint32_t ctrl, op;
+       int mfd, mfn, mfi, pdf, ret;
        uint64_t refclk, temp;
-       int32_t mfn_abs;
+       uint32_t mfn_abs;
 
        ctrl = readl(&pll->ctrl);
 
@@ -189,23 +373,23 @@ static uint32_t decode_pll(struct mxc_pll_reg *pll, uint32_t infreq)
        if (mfn >= 0x04000000) {
                mfn |= 0xfc000000;
                mfn_abs = -mfn;
-       } else
+       } else {
                mfn_abs = mfn;
-
+       }
        refclk = infreq * 2;
        if (ctrl & MXC_DPLLC_CTL_DPDCK0_2_EN)
                refclk *= 2;
 
-       do_div(refclk, pdf + 1);
        temp = refclk * mfn_abs;
        do_div(temp, mfd + 1);
        ret = refclk * mfi;
 
-       if ((int)mfn < 0)
+       if (mfn < 0)
                ret -= temp;
        else
                ret += temp;
 
+       ret /= pdf + 1;
        return ret;
 }
 
@@ -444,6 +628,17 @@ static u32 get_emi_slow_clk(void)
        return  get_periph_clk() / (pdf + 1);
 }
 
+static u32 get_nfc_clk(void)
+{
+       u32 parent_rate = get_emi_slow_clk();
+       u32 div = readl(&mxc_ccm->cbcdr);
+
+       div &= MXC_CCM_CBCDR_NFC_PODF_MASK;
+       div >>= MXC_CCM_CBCDR_NFC_PODF_OFFSET;
+       div++;
+       return parent_rate / div;
+}
+
 static u32 get_ddr_clk(void)
 {
        u32 ret_val = 0;
@@ -513,6 +708,14 @@ unsigned int mxc_get_clock(enum mxc_clock clk)
                return get_ahb_clk();
        case MXC_DDR_CLK:
                return get_ddr_clk();
+       case MXC_AXI_A_CLK:
+               return get_axi_a_clk();
+       case MXC_AXI_B_CLK:
+               return get_axi_b_clk();
+       case MXC_EMI_SLOW_CLK:
+               return get_emi_slow_clk();
+       case MXC_NFC_CLK:
+               return get_nfc_clk();
        default:
                break;
        }
@@ -551,18 +754,17 @@ static int gcd(int m, int n)
  */
 static int calc_pll_params(u32 ref, u32 target, struct pll_param *pll)
 {
-       u64 pd, mfi = 1, mfn, mfd, t1;
-       u32 n_target = target;
-       u32 n_ref = ref, i;
+       int pd, mfi = 1, mfn, mfd;
+       u64 t1;
+       size_t i;
 
        /*
         * Make sure targeted freq is in the valid range.
         * Otherwise the following calculation might be wrong!!!
         */
-       if (n_target < PLL_FREQ_MIN(ref) ||
-               n_target > PLL_FREQ_MAX(ref)) {
-               printf("Targeted peripheral clock should be"
-                       "within [%d - %d]\n",
+       if (target < PLL_FREQ_MIN(ref) ||
+               target > PLL_FREQ_MAX(ref)) {
+               printf("Targeted pll clock should be within [%d - %d]\n",
                        PLL_FREQ_MIN(ref) / SZ_DEC_1M,
                        PLL_FREQ_MAX(ref) / SZ_DEC_1M);
                return -EINVAL;
@@ -578,10 +780,9 @@ static int calc_pll_params(u32 ref, u32 target, struct pll_param *pll)
        if (i == ARRAY_SIZE(fixed_mfd))
                return -EINVAL;
 
-       /* Use n_target and n_ref to avoid overflow */
        for (pd = 1; pd <= PLL_PD_MAX; pd++) {
-               t1 = n_target * pd;
-               do_div(t1, (4 * n_ref));
+               t1 = (u64)target * pd;
+               do_div(t1, (4 * ref));
                mfi = t1;
                if (mfi > PLL_MFI_MAX)
                        return -EINVAL;
@@ -592,25 +793,26 @@ static int calc_pll_params(u32 ref, u32 target, struct pll_param *pll)
        /*
         * Now got pd and mfi already
         *
-        * mfn = (((n_target * pd) / 4 - n_ref * mfi) * mfd) / n_ref;
+        * mfn = (((target * pd) / 4 - ref * mfi) * mfd) / ref;
         */
-       t1 = n_target * pd;
+       t1 = (u64)target * pd;
        do_div(t1, 4);
-       t1 -= n_ref * mfi;
-       t1 *= mfd;
-       do_div(t1, n_ref);
+       t1 = (t1 - ref * mfi) * mfd;
+       do_div(t1, ref);
        mfn = t1;
-       debug("ref=%d, target=%d, pd=%d," "mfi=%d,mfn=%d, mfd=%d\n",
-               ref, n_target, (u32)pd, (u32)mfi, (u32)mfn, (u32)mfd);
-       i = 1;
-       if (mfn != 0)
+       if (mfn != 0) {
                i = gcd(mfd, mfn);
-       pll->pd = (u32)pd;
-       pll->mfi = (u32)mfi;
-       do_div(mfn, i);
-       pll->mfn = (u32)mfn;
-       do_div(mfd, i);
-       pll->mfd = (u32)mfd;
+               mfn /= i;
+               mfd /= i;
+       } else {
+               mfd = 1;
+       }
+       debug("ref=%d, target=%d, pd=%d, mfi=%d, mfn=%d, mfd=%d\n",
+               ref, target, pd, mfi, mfn, mfd);
+       pll->pd = pd;
+       pll->mfi = mfi;
+       pll->mfn = mfn;
+       pll->mfd = mfd;
 
        return 0;
 }
@@ -628,71 +830,63 @@ static int calc_pll_params(u32 ref, u32 target, struct pll_param *pll)
 
 #define CHANGE_PLL_SETTINGS(pll, pd, fi, fn, fd) \
        {       \
-               writel(0x1232, &pll->ctrl);             \
-               writel(0x2, &pll->config);              \
-               writel((((pd) - 1) << 0) | ((fi) << 4), \
-                       &pll->op);                      \
-               writel(fn, &(pll->mfn));                \
-               writel((fd) - 1, &pll->mfd);            \
-               writel((((pd) - 1) << 0) | ((fi) << 4), \
-                       &pll->hfs_op);                  \
-               writel(fn, &pll->hfs_mfn);              \
-               writel((fd) - 1, &pll->hfs_mfd);        \
-               writel(0x1232, &pll->ctrl);             \
-               while (!readl(&pll->ctrl) & 0x1)        \
+               __raw_writel(0x1232, &pll->ctrl);               \
+               __raw_writel(0x2, &pll->config);                \
+               __raw_writel((((pd) - 1) << 0) | ((fi) << 4),   \
+                       &pll->op);                              \
+               __raw_writel(fn, &(pll->mfn));                  \
+               __raw_writel((fd) - 1, &pll->mfd);              \
+               __raw_writel((((pd) - 1) << 0) | ((fi) << 4),   \
+                       &pll->hfs_op);                          \
+               __raw_writel(fn, &pll->hfs_mfn);                \
+               __raw_writel((fd) - 1, &pll->hfs_mfd);          \
+               __raw_writel(0x1232, &pll->ctrl);               \
+               while (!__raw_readl(&pll->ctrl) & 0x1)          \
                        ;\
        }
 
 static int config_pll_clk(enum pll_clocks index, struct pll_param *pll_param)
 {
-       u32 ccsr = readl(&mxc_ccm->ccsr);
+       u32 ccsr = __raw_readl(&mxc_ccm->ccsr);
        struct mxc_pll_reg *pll = mxc_plls[index];
 
        switch (index) {
        case PLL1_CLOCK:
                /* Switch ARM to PLL2 clock */
-               writel(ccsr | MXC_CCM_CCSR_PLL1_SW_CLK_SEL,
-                               &mxc_ccm->ccsr);
+               __raw_writel(ccsr | 0x4, &mxc_ccm->ccsr);
                CHANGE_PLL_SETTINGS(pll, pll_param->pd,
                                        pll_param->mfi, pll_param->mfn,
                                        pll_param->mfd);
                /* Switch back */
-               writel(ccsr & ~MXC_CCM_CCSR_PLL1_SW_CLK_SEL,
-                               &mxc_ccm->ccsr);
+               __raw_writel(ccsr & ~0x4, &mxc_ccm->ccsr);
                break;
        case PLL2_CLOCK:
                /* Switch to pll2 bypass clock */
-               writel(ccsr | MXC_CCM_CCSR_PLL2_SW_CLK_SEL,
-                               &mxc_ccm->ccsr);
+               __raw_writel(ccsr | 0x2, &mxc_ccm->ccsr);
                CHANGE_PLL_SETTINGS(pll, pll_param->pd,
                                        pll_param->mfi, pll_param->mfn,
                                        pll_param->mfd);
                /* Switch back */
-               writel(ccsr & ~MXC_CCM_CCSR_PLL2_SW_CLK_SEL,
-                               &mxc_ccm->ccsr);
+               __raw_writel(ccsr & ~0x2, &mxc_ccm->ccsr);
                break;
        case PLL3_CLOCK:
                /* Switch to pll3 bypass clock */
-               writel(ccsr | MXC_CCM_CCSR_PLL3_SW_CLK_SEL,
-                               &mxc_ccm->ccsr);
+               __raw_writel(ccsr | 0x1, &mxc_ccm->ccsr);
                CHANGE_PLL_SETTINGS(pll, pll_param->pd,
                                        pll_param->mfi, pll_param->mfn,
                                        pll_param->mfd);
                /* Switch back */
-               writel(ccsr & ~MXC_CCM_CCSR_PLL3_SW_CLK_SEL,
-                               &mxc_ccm->ccsr);
+               __raw_writel(ccsr & ~0x1, &mxc_ccm->ccsr);
                break;
 #ifdef CONFIG_MX53
        case PLL4_CLOCK:
                /* Switch to pll4 bypass clock */
-               writel(ccsr | MXC_CCM_CCSR_PLL4_SW_CLK_SEL,
-                               &mxc_ccm->ccsr);
+               __raw_writel(ccsr | 0x20, &mxc_ccm->ccsr);
                CHANGE_PLL_SETTINGS(pll, pll_param->pd,
                                        pll_param->mfi, pll_param->mfn,
                                        pll_param->mfd);
                /* Switch back */
-               writel(ccsr & ~MXC_CCM_CCSR_PLL4_SW_CLK_SEL,
-                               &mxc_ccm->ccsr);
+               __raw_writel(ccsr & ~0x20, &mxc_ccm->ccsr);
                break;
 #endif
        default:
@@ -702,22 +896,60 @@ static int config_pll_clk(enum pll_clocks index, struct pll_param *pll_param)
        return 0;
 }
 
+static int __adjust_core_voltage_stub(u32 freq)
+{
+       return 0;
+}
+int adjust_core_voltage(u32 freq)
+       __attribute__((weak, alias("__adjust_core_voltage_stub")));
+
 /* Config CPU clock */
 static int config_core_clk(u32 ref, u32 freq)
 {
        int ret = 0;
        struct pll_param pll_param;
+       u32 cur_freq = decode_pll(mxc_plls[PLL1_CLOCK], MXC_HCLK);
+
+       if (freq == cur_freq)
+               return 0;
 
        memset(&pll_param, 0, sizeof(struct pll_param));
 
        /* The case that periph uses PLL1 is not considered here */
        ret = calc_pll_params(ref, freq, &pll_param);
        if (ret != 0) {
-               printf("Error:Can't find pll parameters: %d\n", ret);
+               printf("Error: Can't find pll parameters for %u.%03uMHz ref %u.%03uMHz\n",
+                       freq / 1000000, freq / 1000 % 1000,
+                       ref / 1000000, ref / 1000 % 1000);
                return ret;
        }
-
-       return config_pll_clk(PLL1_CLOCK, &pll_param);
+       if (freq > cur_freq) {
+               ret = adjust_core_voltage(freq);
+               if (ret < 0) {
+                       printf("Failed to adjust core voltage for changing ARM clk from %u.%03uMHz to  %u.%03uMHz\n",
+                               cur_freq / 1000000, cur_freq / 1000 % 1000,
+                               freq / 1000000, freq / 1000 % 1000);
+                       return ret;
+               }
+               ret = config_pll_clk(PLL1_CLOCK, &pll_param);
+               if (ret) {
+                       adjust_core_voltage(cur_freq);
+               }
+       } else {
+               ret = config_pll_clk(PLL1_CLOCK, &pll_param);
+               if (ret) {
+                       return ret;
+               }
+               ret = adjust_core_voltage(freq);
+               if (ret < 0) {
+                       printf("Failed to adjust core voltage for changing ARM clk from %u.%03uMHz to  %u.%03uMHz\n",
+                               cur_freq / 1000000, cur_freq / 1000 % 1000,
+                               freq / 1000000, freq / 1000 % 1000);
+                       calc_pll_params(ref, cur_freq, &pll_param);
+                       config_pll_clk(PLL1_CLOCK, &pll_param);
+               }
+       }
+       return ret;
 }
 
 static int config_nfc_clk(u32 nfc_clk)
@@ -914,36 +1146,118 @@ void mxc_set_sata_internal_clock(void)
 /*
  * Dump some core clockes.
  */
-int do_mx5_showclocks(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+#define pr_clk_val(c, v) {                                     \
+       printf("%-11s %3lu.%03lu MHz\n", #c,                    \
+               (v) / 1000000, (v) / 1000 % 1000);              \
+}
+
+#define pr_clk(c) {                                            \
+       unsigned long __clk = mxc_get_clock(MXC_##c##_CLK);     \
+       pr_clk_val(c, __clk);                                   \
+}
+
+static int do_mx5_showclocks(void)
 {
-       u32 freq;
+       unsigned long freq;
 
        freq = decode_pll(mxc_plls[PLL1_CLOCK], MXC_HCLK);
-       printf("PLL1       %8d MHz\n", freq / 1000000);
+       pr_clk_val(PLL1, freq);
        freq = decode_pll(mxc_plls[PLL2_CLOCK], MXC_HCLK);
-       printf("PLL2       %8d MHz\n", freq / 1000000);
+       pr_clk_val(PLL2, freq);
        freq = decode_pll(mxc_plls[PLL3_CLOCK], MXC_HCLK);
-       printf("PLL3       %8d MHz\n", freq / 1000000);
+       pr_clk_val(PLL3, freq);
 #ifdef CONFIG_MX53
        freq = decode_pll(mxc_plls[PLL4_CLOCK], MXC_HCLK);
-       printf("PLL4       %8d MHz\n", freq / 1000000);
+       pr_clk_val(PLL4, freq);
 #endif
 
        printf("\n");
-       printf("AHB        %8d kHz\n", mxc_get_clock(MXC_AHB_CLK) / 1000);
-       printf("IPG        %8d kHz\n", mxc_get_clock(MXC_IPG_CLK) / 1000);
-       printf("IPG PERCLK %8d kHz\n", mxc_get_clock(MXC_IPG_PERCLK) / 1000);
-       printf("DDR        %8d kHz\n", mxc_get_clock(MXC_DDR_CLK) / 1000);
+       pr_clk(AHB);
+       pr_clk(AXI_A);
+       pr_clk(AXI_B);
+       pr_clk(IPG);
+       pr_clk(IPG_PER);
+       pr_clk(DDR);
+       pr_clk(EMI_SLOW);
+       pr_clk(NFC);
 #ifdef CONFIG_MXC_SPI
-       printf("CSPI       %8d kHz\n", mxc_get_clock(MXC_CSPI_CLK) / 1000);
+       pr_clk(CSPI);
 #endif
        return 0;
 }
 
+static struct clk_lookup {
+       const char *name;
+       unsigned int index;
+} mx5_clk_lookup[] = {
+       { "arm", MXC_ARM_CLK, },
+};
+
+int do_clocks(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
+{
+       int i;
+       unsigned long freq;
+       unsigned long ref = ~0UL;
+
+       if (argc < 2) {
+               do_mx5_showclocks();
+               return CMD_RET_SUCCESS;
+       } else if (argc == 2 || argc > 4) {
+               return CMD_RET_USAGE;
+       }
+
+       freq = simple_strtoul(argv[2], NULL, 0);
+       if (freq == 0) {
+               printf("Invalid clock frequency %lu\n", freq);
+               return CMD_RET_FAILURE;
+       }
+       if (argc > 3) {
+               ref = simple_strtoul(argv[3], NULL, 0);
+       }
+       for (i = 0; i < ARRAY_SIZE(mx5_clk_lookup); i++) {
+               if (strcasecmp(argv[1], mx5_clk_lookup[i].name) == 0) {
+                       switch (mx5_clk_lookup[i].index) {
+                       case MXC_ARM_CLK:
+                               if (argc > 3)
+                                       return CMD_RET_USAGE;
+                               ref = CONFIG_SYS_MX5_HCLK;
+                               break;
+
+                       case MXC_NFC_CLK:
+                               if (argc > 3 && ref > 3) {
+                                       printf("Invalid clock selector value: %lu\n", ref);
+                                       return CMD_RET_FAILURE;
+                               }
+                               break;
+                       }
+                       printf("Setting %s clock to %lu MHz\n",
+                               mx5_clk_lookup[i].name, freq);
+                       if (mxc_set_clock(ref, freq, mx5_clk_lookup[i].index))
+                               break;
+                       freq = mxc_get_clock(mx5_clk_lookup[i].index);
+                       printf("%s clock set to %lu.%03lu MHz\n",
+                               mx5_clk_lookup[i].name,
+                               freq / 1000000, freq / 1000 % 1000);
+                       return CMD_RET_SUCCESS;
+               }
+       }
+       if (i == ARRAY_SIZE(mx5_clk_lookup)) {
+               printf("clock %s not found; supported clocks are:\n", argv[1]);
+               for (i = 0; i < ARRAY_SIZE(mx5_clk_lookup); i++) {
+                       printf("\t%s\n", mx5_clk_lookup[i].name);
+               }
+       } else {
+               printf("Failed to set clock %s to %s MHz\n",
+                       argv[1], argv[2]);
+       }
+       return CMD_RET_FAILURE;
+}
+
 /***************************************************/
 
 U_BOOT_CMD(
-       clocks, CONFIG_SYS_MAXARGS, 1, do_mx5_showclocks,
-       "display clocks",
-       ""
+       clocks, 4, 0, do_clocks,
+       "display/set clocks",
+       "                    - display clock settings\n"
+       "clocks <clkname> <freq>    - set clock <clkname> to <freq> MHz"
 );