/* SPDX-License-Identifier: GPL-2.0-only */ #include #include #include #include #include #include #include #include #include #include #include #include #include struct pll_div { u32 nr; u32 nf; u32 no; }; struct rk3288_cru_reg { u32 cru_apll_con[4]; u32 cru_dpll_con[4]; u32 cru_cpll_con[4]; u32 cru_gpll_con[4]; u32 cru_npll_con[4]; u32 cru_mode_con; u32 reserved0[3]; u32 cru_clksel_con[43]; u32 reserved1[21]; u32 cru_clkgate_con[19]; u32 reserved2; u32 cru_glb_srst_fst_value; u32 cru_glb_srst_snd_value; u32 cru_softrst_con[12]; u32 cru_misc_con; u32 cru_glb_cnt_th; u32 cru_glb_rst_con; u32 reserved3; u32 cru_glb_rst_st; u32 reserved4; u32 cru_sdmmc_con[2]; u32 cru_sdio0_con[2]; u32 cru_sdio1_con[2]; u32 cru_emmc_con[2]; }; check_member(rk3288_cru_reg, cru_emmc_con[1], 0x021c); static struct rk3288_cru_reg * const cru_ptr = (void *)CRU_BASE; #define PLL_DIVISORS(hz, _nr, _no) {\ .nr = _nr, .nf = (u32)((u64)hz * _nr * _no / OSC_HZ), .no = _no};\ _Static_assert(((u64)hz * _nr * _no / OSC_HZ) * OSC_HZ /\ (_nr * _no) == hz, #hz "Hz cannot be hit with PLL "\ "divisors on line " STRINGIFY(__LINE__)) /* Keep divisors as low as possible to reduce jitter and power usage. */ static const struct pll_div gpll_init_cfg = PLL_DIVISORS(GPLL_HZ, 2, 2); static const struct pll_div cpll_init_cfg = PLL_DIVISORS(CPLL_HZ, 1, 2); /* See linux/drivers/clk/rockchip/clk-rk3288.c for more APLL combinations */ static const struct pll_div apll_1800_cfg = PLL_DIVISORS(1800*MHz, 1, 1); static const struct pll_div apll_1416_cfg = PLL_DIVISORS(1416*MHz, 1, 1); static const struct pll_div apll_600_cfg = PLL_DIVISORS(600*MHz, 1, 2); static const struct pll_div *apll_cfgs[] = { [APLL_1800_MHZ] = &apll_1800_cfg, [APLL_1416_MHZ] = &apll_1416_cfg, [APLL_600_MHZ] = &apll_600_cfg, }; /*******************PLL CON0 BITS***************************/ #define PLL_OD_MSK (0x0F) #define PLL_NR_MSK (0x3F << 8) #define PLL_NR_SHIFT (8) /*******************PLL CON1 BITS***************************/ #define PLL_NF_MSK (0x1FFF) /*******************PLL CON2 BITS***************************/ #define PLL_BWADJ_MSK (0x0FFF) /*******************PLL CON3 BITS***************************/ #define PLL_RESET_MSK (1 << 5) #define PLL_RESET (1 << 5) #define PLL_RESET_RESUME (0 << 5) /*******************CLKSEL0 BITS***************************/ /* core clk pll sel: amr or general */ #define CORE_SEL_PLL_MSK (1 << 15) #define CORE_SEL_APLL (0 << 15) #define CORE_SEL_GPLL (1 << 15) /* a12 core clock div: clk_core = clk_src / (div_con + 1) */ #define A12_DIV_SHIFT (8) #define A12_DIV_MSK (0x1F << 8) /* mp core axi clock div: clk = clk_src / (div_con + 1) */ #define MP_DIV_SHIFT (4) #define MP_DIV_MSK (0xF << 4) /* m0 core axi clock div: clk = clk_src / (div_con + 1) */ #define M0_DIV_MSK (0xF) /*******************CLKSEL1 BITS***************************/ /* pd bus clk pll sel: codec or general */ #define PD_BUS_SEL_PLL_MSK (1 << 15) #define PD_BUS_SEL_CPLL (0 << 15) #define PD_BUS_SEL_GPLL (1 << 15) /* pd bus pclk div: * pclk = pd_bus_aclk /(div + 1) */ #define PD_BUS_PCLK_DIV_SHIFT (12) #define PD_BUS_PCLK_DIV_MSK (0x7 << 12) /* pd bus hclk div: * aclk_bus: hclk_bus = 1:1 or 2:1 or 4:1 */ #define PD_BUS_HCLK_DIV_SHIFT (8) #define PD_BUS_HCLK_DIV_MSK (0x3 << 8) /* pd bus aclk div: * pd_bus_aclk = pd_bus_src_clk /(div0 * div1) */ #define PD_BUS_ACLK_DIV0_SHIFT (3) #define PD_BUS_ACLK_DIV0_MASK (0x1f << 3) #define PD_BUS_ACLK_DIV1_SHIFT (0) #define PD_BUS_ACLK_DIV1_MASK (0x7 << 0) /*******************CLKSEL10 BITS***************************/ /* peripheral bus clk pll sel: codec or general */ #define PERI_SEL_PLL_MSK (1 << 15) #define PERI_SEL_CPLL (0 << 15) #define PERI_SEL_GPLL (1 << 15) /* peripheral bus pclk div: * aclk_bus: pclk_bus = 1:1 or 2:1 or 4:1 or 8:1 */ #define PERI_PCLK_DIV_SHIFT (12) #define PERI_PCLK_DIV_MSK (0x7 << 12) /* peripheral bus hclk div: * aclk_bus: hclk_bus = 1:1 or 2:1 or 4:1 */ #define PERI_HCLK_DIV_SHIFT (8) #define PERI_HCLK_DIV_MSK (0x3 << 8) /* peripheral bus aclk div: * aclk_periph = * periph_clk_src / (peri_aclk_div_con + 1) */ #define PERI_ACLK_DIV_SHIFT (0x0) #define PERI_ACLK_DIV_MSK (0x1F) /*******************CLKSEL37 BITS***************************/ #define L2_DIV_MSK (0x7) #define ATCLK_DIV_MSK (0x1F << 4) #define ATCLK_DIV_SHIFT (4) #define PCLK_DBG_DIV_MSK (0x1F << 9) #define PCLK_DBG_DIV_SHIFT (9) #define APLL_MODE_MSK (0x3) #define APLL_MODE_SLOW (0) #define APLL_MODE_NORM (1) #define DPLL_MODE_MSK (0x3 << 4) #define DPLL_MODE_SLOW (0 << 4) #define DPLL_MODE_NORM (1 << 4) #define CPLL_MODE_MSK (0x3 << 8) #define CPLL_MODE_SLOW (0 << 8) #define CPLL_MODE_NORM (1 << 8) #define GPLL_MODE_MSK (0x3 << 12) #define GPLL_MODE_SLOW (0 << 12) #define GPLL_MODE_NORM (1 << 12) #define NPLL_MODE_MSK (0x3 << 14) #define NPLL_MODE_SLOW (0 << 14) #define NPLL_MODE_NORM (1 << 14) #define SOCSTS_DPLL_LOCK (1 << 5) #define SOCSTS_APLL_LOCK (1 << 6) #define SOCSTS_CPLL_LOCK (1 << 7) #define SOCSTS_GPLL_LOCK (1 << 8) #define SOCSTS_NPLL_LOCK (1 << 9) #define VCO_MAX_KHZ (2200 * (MHz/KHz)) #define VCO_MIN_KHZ (440 * (MHz/KHz)) #define OUTPUT_MAX_KHZ (2200 * (MHz/KHz)) #define OUTPUT_MIN_KHZ 27500 #define FREF_MAX_KHZ (2200 * (MHz/KHz)) #define FREF_MIN_KHZ 269 static int rkclk_set_pll(u32 *pll_con, const struct pll_div *div) { /* All PLLs have same VCO and output frequency range restrictions. */ u32 vco_khz = OSC_HZ/KHz * div->nf / div->nr; u32 output_khz = vco_khz / div->no; printk(BIOS_DEBUG, "Configuring PLL at %p with NF = %d, NR = %d and " "NO = %d (VCO = %uKHz, output = %uKHz)\n", pll_con, div->nf, div->nr, div->no, vco_khz, output_khz); assert(vco_khz >= VCO_MIN_KHZ && vco_khz <= VCO_MAX_KHZ && output_khz >= OUTPUT_MIN_KHZ && output_khz <= OUTPUT_MAX_KHZ && (div->no == 1 || !(div->no % 2))); /* enter rest */ write32(&pll_con[3], RK_SETBITS(PLL_RESET_MSK)); write32(&pll_con[0], RK_CLRSETBITS(PLL_NR_MSK, (div->nr - 1) << PLL_NR_SHIFT) | RK_CLRSETBITS(PLL_OD_MSK, (div->no - 1))); write32(&pll_con[1], RK_CLRSETBITS(PLL_NF_MSK, (div->nf - 1))); write32(&pll_con[2], RK_CLRSETBITS(PLL_BWADJ_MSK, ((div->nf >> 1) - 1))); udelay(10); /* return form rest */ write32(&pll_con[3], RK_CLRBITS(PLL_RESET_MSK)); return 0; } void rkclk_init(void) { u32 aclk_div; u32 hclk_div; u32 pclk_div; /* pll enter slow-mode */ write32(&cru_ptr->cru_mode_con, RK_CLRSETBITS(GPLL_MODE_MSK, GPLL_MODE_SLOW) | RK_CLRSETBITS(CPLL_MODE_MSK, CPLL_MODE_SLOW)); /* init pll */ rkclk_set_pll(&cru_ptr->cru_gpll_con[0], &gpll_init_cfg); rkclk_set_pll(&cru_ptr->cru_cpll_con[0], &cpll_init_cfg); /* waiting for pll lock */ while (1) { if ((read32(&rk3288_grf->soc_status[1]) & (SOCSTS_CPLL_LOCK | SOCSTS_GPLL_LOCK)) == (SOCSTS_CPLL_LOCK | SOCSTS_GPLL_LOCK)) break; udelay(1); } /* * pd_bus clock pll source selection and * set up dependent divisors for PCLK/HCLK and ACLK clocks. */ aclk_div = GPLL_HZ / PD_BUS_ACLK_HZ - 1; assert((aclk_div + 1) * PD_BUS_ACLK_HZ == GPLL_HZ && aclk_div <= 0x1f); hclk_div = PD_BUS_ACLK_HZ / PD_BUS_HCLK_HZ - 1; assert((hclk_div + 1) * PD_BUS_HCLK_HZ == PD_BUS_ACLK_HZ && (hclk_div <= 0x3) && (hclk_div != 0x2)); pclk_div = PD_BUS_ACLK_HZ / PD_BUS_PCLK_HZ - 1; assert((pclk_div + 1) * PD_BUS_PCLK_HZ == PD_BUS_ACLK_HZ && pclk_div <= 0x7); write32(&cru_ptr->cru_clksel_con[1], RK_SETBITS(PD_BUS_SEL_GPLL) | RK_CLRSETBITS(PD_BUS_PCLK_DIV_MSK, pclk_div << PD_BUS_PCLK_DIV_SHIFT) | RK_CLRSETBITS(PD_BUS_HCLK_DIV_MSK, hclk_div << PD_BUS_HCLK_DIV_SHIFT) | RK_CLRSETBITS(PD_BUS_ACLK_DIV0_MASK, aclk_div << PD_BUS_ACLK_DIV0_SHIFT) | RK_CLRSETBITS(PD_BUS_ACLK_DIV1_MASK, 0 << 0)); /* * peri clock pll source selection and * set up dependent divisors for PCLK/HCLK and ACLK clocks. */ aclk_div = GPLL_HZ / PERI_ACLK_HZ - 1; assert((aclk_div + 1) * PERI_ACLK_HZ == GPLL_HZ && aclk_div <= 0x1f); hclk_div = log2(PERI_ACLK_HZ / PERI_HCLK_HZ); assert((1 << hclk_div) * PERI_HCLK_HZ == PERI_ACLK_HZ && (hclk_div <= 0x2)); pclk_div = log2(PERI_ACLK_HZ / PERI_PCLK_HZ); assert((1 << pclk_div) * PERI_PCLK_HZ == PERI_ACLK_HZ && (pclk_div <= 0x3)); write32(&cru_ptr->cru_clksel_con[10], RK_SETBITS(PERI_SEL_GPLL) | RK_CLRSETBITS(PERI_PCLK_DIV_MSK, pclk_div << PERI_PCLK_DIV_SHIFT) | RK_CLRSETBITS(PERI_HCLK_DIV_MSK, hclk_div << PERI_HCLK_DIV_SHIFT) | RK_CLRSETBITS(PERI_ACLK_DIV_MSK, aclk_div << PERI_ACLK_DIV_SHIFT)); /* PLL enter normal-mode */ write32(&cru_ptr->cru_mode_con, RK_CLRSETBITS(GPLL_MODE_MSK, GPLL_MODE_NORM) | RK_CLRSETBITS(CPLL_MODE_MSK, CPLL_MODE_NORM)); } void rkclk_configure_cpu(enum apll_frequencies apll_freq) { /* pll enter slow-mode */ write32(&cru_ptr->cru_mode_con, RK_CLRSETBITS(APLL_MODE_MSK, APLL_MODE_SLOW)); rkclk_set_pll(&cru_ptr->cru_apll_con[0], apll_cfgs[apll_freq]); /* waiting for pll lock */ while (1) { if (read32(&rk3288_grf->soc_status[1]) & SOCSTS_APLL_LOCK) break; udelay(1); } /* * core clock pll source selection and * set up dependent divisors for MPAXI/M0AXI and ARM clocks. * core clock select apll, apll clk = 1800MHz * arm clk = 1800MHz, mpclk = 450MHz, m0clk = 900MHz */ write32(&cru_ptr->cru_clksel_con[0], RK_CLRBITS(CORE_SEL_PLL_MSK) | RK_CLRSETBITS(A12_DIV_MSK, 0 << A12_DIV_SHIFT) | RK_CLRSETBITS(MP_DIV_MSK, 3 << MP_DIV_SHIFT) | RK_CLRSETBITS(M0_DIV_MSK, 1 << 0)); /* * set up dependent divisors for L2RAM/ATCLK and PCLK clocks. * l2ramclk = 900MHz, atclk = 450MHz, pclk_dbg = 450MHz */ write32(&cru_ptr->cru_clksel_con[37], RK_CLRSETBITS(L2_DIV_MSK, 1 << 0) | RK_CLRSETBITS(ATCLK_DIV_MSK, (3 << ATCLK_DIV_SHIFT)) | RK_CLRSETBITS(PCLK_DBG_DIV_MSK, (3 << PCLK_DBG_DIV_SHIFT))); /* PLL enter normal-mode */ write32(&cru_ptr->cru_mode_con, RK_CLRSETBITS(APLL_MODE_MSK, APLL_MODE_NORM)); } void rkclk_configure_ddr(unsigned int hz) { struct pll_div dpll_cfg; switch (hz) { case 300*MHz: dpll_cfg = (struct pll_div){.nf = 50, .nr = 2, .no = 2}; break; case 533*MHz: /* actually 533.3P MHz */ dpll_cfg = (struct pll_div){.nf = 400, .nr = 9, .no = 2}; break; case 666*MHz: /* actually 666.6P MHz */ dpll_cfg = (struct pll_div){.nf = 500, .nr = 9, .no = 2}; break; case 800*MHz: dpll_cfg = (struct pll_div){.nf = 100, .nr = 3, .no = 1}; break; default: die("Unsupported SDRAM frequency, add to clock.c!"); } /* pll enter slow-mode */ write32(&cru_ptr->cru_mode_con, RK_CLRSETBITS(DPLL_MODE_MSK, DPLL_MODE_SLOW)); rkclk_set_pll(&cru_ptr->cru_dpll_con[0], &dpll_cfg); /* waiting for pll lock */ while (1) { if (read32(&rk3288_grf->soc_status[1]) & SOCSTS_DPLL_LOCK) break; udelay(1); } /* PLL enter normal-mode */ write32(&cru_ptr->cru_mode_con, RK_CLRSETBITS(DPLL_MODE_MSK, DPLL_MODE_NORM)); } void rkclk_ddr_reset(u32 ch, u32 ctl, u32 phy) { u32 phy_ctl_srstn_shift = 4 + 5 * ch; u32 ctl_psrstn_shift = 3 + 5 * ch; u32 ctl_srstn_shift = 2 + 5 * ch; u32 phy_psrstn_shift = 1 + 5 * ch; u32 phy_srstn_shift = 5 * ch; write32(&cru_ptr->cru_softrst_con[10], RK_CLRSETBITS(1 << phy_ctl_srstn_shift, phy << phy_ctl_srstn_shift) | RK_CLRSETBITS(1 << ctl_psrstn_shift, ctl << ctl_psrstn_shift) | RK_CLRSETBITS(1 << ctl_srstn_shift, ctl << ctl_srstn_shift) | RK_CLRSETBITS(1 << phy_psrstn_shift, phy << phy_psrstn_shift) | RK_CLRSETBITS(1 << phy_srstn_shift, phy << phy_srstn_shift)); } void rkclk_ddr_phy_ctl_reset(u32 ch, u32 n) { u32 phy_ctl_srstn_shift = 4 + 5 * ch; write32(&cru_ptr->cru_softrst_con[10], RK_CLRSETBITS(1 << phy_ctl_srstn_shift, n << phy_ctl_srstn_shift)); } void rkclk_configure_spi(unsigned int bus, unsigned int hz) { int src_clk_div = GPLL_HZ / hz; assert((src_clk_div - 1 <= 127) && (src_clk_div * hz == GPLL_HZ)); switch (bus) { /*select gpll as spi src clk, and set div*/ case 0: write32(&cru_ptr->cru_clksel_con[25], RK_CLRSETBITS(1 << 7 | 0x1f << 0, 1 << 7 | (src_clk_div - 1) << 0)); break; case 1: write32(&cru_ptr->cru_clksel_con[25], RK_CLRSETBITS(1 << 15 | 0x1f << 8, 1 << 15 | (src_clk_div - 1) << 8)); break; case 2: write32(&cru_ptr->cru_clksel_con[39], RK_CLRSETBITS(1 << 7 | 0x1f << 0, 1 << 7 | (src_clk_div - 1) << 0)); break; default: printk(BIOS_ERR, "do not support this spi bus\n"); } } void rkclk_configure_i2s(unsigned int hz) { int n, d; int v; /* i2s source clock: gpll i2s0_outclk_sel: clk_i2s i2s0_clk_sel: divider output from fraction i2s0_pll_div_con: 0*/ write32(&cru_ptr->cru_clksel_con[4], RK_CLRSETBITS(1 << 15 | 1 << 12 | 3 << 8 | 0x7f << 0, 1 << 15 | 0 << 12 | 1 << 8 | 0 << 0)); /* set frac divider */ v = gcd(GPLL_HZ, hz); n = (GPLL_HZ / v) & (0xffff); d = (hz / v) & (0xffff); assert(hz == GPLL_HZ / n * d); write32(&cru_ptr->cru_clksel_con[8], d << 16 | n); } void rkclk_configure_crypto(unsigned int hz) { u32 div = PD_BUS_ACLK_HZ / hz; assert((div - 1 <= 3) && (div * hz == PD_BUS_ACLK_HZ)); assert(hz <= 150*MHz); /* Suggested max in TRM. */ write32(&cru_ptr->cru_clksel_con[26], RK_CLRSETBITS(0x3 << 6, (div - 1) << 6)); } void rkclk_configure_tsadc(unsigned int hz) { u32 div; u32 src_clk = 32 * KHz; /* tsadc source clock is 32KHz*/ div = src_clk / hz; assert((div - 1 <= 63) && (div * hz == 32 * KHz)); write32(&cru_ptr->cru_clksel_con[2], RK_CLRSETBITS(0x3f << 0, (div - 1) << 0)); } static int pll_para_config(u32 freq_hz, struct pll_div *div, u32 *ext_div) { u32 ref_khz = OSC_HZ / KHz, nr, nf = 0; u32 fref_khz; u32 diff_khz, best_diff_khz; const u32 max_nr = 1 << 6, max_nf = 1 << 12, max_no = 1 << 4; u32 vco_khz; u32 no = 1; u32 freq_khz = freq_hz / KHz; if (!freq_hz) { printk(BIOS_ERR, "%s: the frequency can not be 0 Hz\n", __func__); return -1; } no = DIV_ROUND_UP(VCO_MIN_KHZ, freq_khz); if (ext_div) { *ext_div = DIV_ROUND_UP(no, max_no); no = DIV_ROUND_UP(no, *ext_div); } /* only even divisors (and 1) are supported */ if (no > 1) no = DIV_ROUND_UP(no, 2) * 2; vco_khz = freq_khz * no; if (ext_div) vco_khz *= *ext_div; if (vco_khz < VCO_MIN_KHZ || vco_khz > VCO_MAX_KHZ || no > max_no) { printk(BIOS_ERR, "%s: Cannot find out a supported VCO" " for Frequency (%uHz).\n", __func__, freq_hz); return -1; } div->no = no; best_diff_khz = vco_khz; for (nr = 1; nr < max_nr && best_diff_khz; nr++) { fref_khz = ref_khz / nr; if (fref_khz < FREF_MIN_KHZ) break; if (fref_khz > FREF_MAX_KHZ) continue; nf = vco_khz / fref_khz; if (nf >= max_nf) continue; diff_khz = vco_khz - nf * fref_khz; if (nf + 1 < max_nf && diff_khz > fref_khz / 2) { nf++; diff_khz = fref_khz - diff_khz; } if (diff_khz >= best_diff_khz) continue; best_diff_khz = diff_khz; div->nr = nr; div->nf = nf; } if (best_diff_khz > 4 * (MHz/KHz)) { printk(BIOS_ERR, "%s: Failed to match output frequency %u, " "difference is %u Hz,exceed 4MHZ\n", __func__, freq_hz, best_diff_khz * KHz); return -1; } return 0; } void rkclk_configure_edp(void) { /* clk_edp_24M source: 24M */ write32(&cru_ptr->cru_clksel_con[28], RK_SETBITS(1 << 15)); /* rst edp */ write32(&cru_ptr->cru_softrst_con[6], RK_SETBITS(1 << 15)); udelay(1); write32(&cru_ptr->cru_softrst_con[6], RK_CLRBITS(1 << 15)); } void rkclk_configure_hdmi(void) { /* enable pclk hdmi ctrl */ write32(&cru_ptr->cru_clkgate_con[16], RK_CLRBITS(1 << 9)); /* software reset hdmi */ write32(&cru_ptr->cru_softrst_con[7], RK_SETBITS(1 << 9)); udelay(1); write32(&cru_ptr->cru_softrst_con[7], RK_CLRBITS(1 << 9)); } void rkclk_configure_vop_aclk(u32 vop_id, u32 aclk_hz) { u32 div; /* vop aclk source clk: cpll */ div = CPLL_HZ / aclk_hz; assert((div - 1 <= 63) && (div * aclk_hz == CPLL_HZ)); switch (vop_id) { case 0: write32(&cru_ptr->cru_clksel_con[31], RK_CLRSETBITS(3 << 6 | 0x1f << 0, 0 << 6 | (div - 1) << 0)); break; case 1: write32(&cru_ptr->cru_clksel_con[31], RK_CLRSETBITS(3 << 14 | 0x1f << 8, 0 << 14 | (div - 1) << 8)); break; } } int rkclk_configure_vop_dclk(u32 vop_id, u32 dclk_hz) { struct pll_div npll_config = {0}; u32 lcdc_div; if (pll_para_config(dclk_hz, &npll_config, &lcdc_div)) return -1; /* npll enter slow-mode */ write32(&cru_ptr->cru_mode_con, RK_CLRSETBITS(NPLL_MODE_MSK, NPLL_MODE_SLOW)); rkclk_set_pll(&cru_ptr->cru_npll_con[0], &npll_config); /* waiting for pll lock */ while (1) { if (read32(&rk3288_grf->soc_status[1]) & SOCSTS_NPLL_LOCK) break; udelay(1); } /* npll enter normal-mode */ write32(&cru_ptr->cru_mode_con, RK_CLRSETBITS(NPLL_MODE_MSK, NPLL_MODE_NORM)); /* vop dclk source clk: npll,dclk_div: 1 */ switch (vop_id) { case 0: write32(&cru_ptr->cru_clksel_con[27], RK_CLRSETBITS(0xff << 8 | 3 << 0, (lcdc_div - 1) << 8 | 2 << 0)); break; case 1: write32(&cru_ptr->cru_clksel_con[29], RK_CLRSETBITS(0xff << 8 | 3 << 6, (lcdc_div - 1) << 8 | 2 << 6)); break; } return 0; } int rkclk_was_watchdog_reset(void) { /* Bits 5 and 4 are "second" and "first" global watchdog reset. */ return read32(&cru_ptr->cru_glb_rst_st) & 0x30; } unsigned int rkclk_i2c_clock_for_bus(unsigned int bus) { /*i2c0,i2c2 src clk from pd_bus_pclk other i2c src clk from peri_pclk */ switch (bus) { case 0: case 2: return PD_BUS_PCLK_HZ; case 1: case 3: case 4: case 5: return PERI_PCLK_HZ; default: return -1; /* Should never happen. */ } }